The Rudolf Steiner Archive

My dear Friends,

I will begin by placing before you what we may call the “Ur-phenomenon”—primary phenomenon—of the Theory of Colour. By and by, you will find it confirmed and reinforced in the phenomena you can observe through the whole range of so-called optics or Theory of Colour. Of course the phenomena get complicated; the simple Ur-phenomenon is not always easy to recognize at once. But if you take the trouble you will find it everywhere. The simple phenomenon—expressed in Goethe's way, to begin with—is as follows: When I look through darkness at something lighter, the light object will appear modified by the darkness in the direction of the light colours, i.e. in the direction of the red and yellowish tones. If for example I look at anything luminous and, as we should call it, white—at any whitish-shining light through a thick enough plate which is in some way dim or cloudy, then what would seem to me more or less white if I were looking at directly, will appear yellowish or yellow-red (Figure IVa).

This is the one pole. Conversely, if you have here a simple black surface and look at it directly, you will see it black, but if you interpose a trough of water through which you send a stream of light so that the liquid is illumined, you will be looking at the dark through something light. Blue or violet (bluish-red) tones of colour will appear (Figure IVb). The other pole is thus revealed. This therefore is the Ur-phenomenon: Light through dark—yellow; dark through light—blue.

This simple phenomenon can be seen on every hand if we once accustom ourselves to think more realistically and not so abstractly as in modern science. Please now recall from this point of view the experiment which we have done. We sent a cylinder of light through a prism and so obtained a real scale of colours, from violet to red; we caught it on a screen. I made a drawing of the phenomenon (see Figure IIc and Figure IVc). You will remember; if this is the prism and this the cylinder of light, the light in some way goes through the prism and is diverted upward. Moreover, as we said before, it is not only diverted. It would be simply diverted if a transparent body with parallel faces were interposed. But we are putting a prism into the path of the light—that is, a body with convergent faces. In passing through the prism, the light gets darkened. The moment we send the light through the prism we therefore have to do with two things: first the simple light as it streams on, and then the dimness interposed in the path of the light. Moreover this dimness, as we said, puts itself into the path of the light in such a way that while the light is mainly diverted upward, the dimming that arises, raying upward as it does, shines also in the same direction into which the light itself is diverted. That is to say, darkness rays into the diverted light. Darkness is living, as it were, in the diverted light, and by this means the bluish and violet shades are here produced. But the darkness rays downward too, so, while the cylinder of light is diverted upward, the darkness here rays downward and works contrary to the diverted light but is no match for it. Here therefore we may say: the original bright light, diverted as it is, overwhelms and outdoes the darkness. We get the yellowish or yellow-red colours.

If we now take a sufficiently thin cylinder of light, we can also look in the direction of it through the prism. Instead of looking from outside on to a screen and seeing the picture projected there, we put our eye in the place of this picture, and, looking through the prism, we then see the aperture, through which the cylinder of light is produced, displaced (Figure IVc). Once again therefore adhering strictly to the facts, we have the following phenomenon: Looking along here, I see what would be coming directly towards me if the prism were not there, displaced in a downward direction by the prism. At the same time I see it coloured.

What then do you see in this case? Watch what you see, state it simply and then connect it with the fundamental fact we have just now been ascertaining. Then, what you actually see will emerge in all detail. Only you must hold to what is really seen. For if you are looking thus into the bright cylinder of light—which, once again, is coming now towards you—you see something light, namely the cylinder of light itself, but you are seeing it through dark. (That there is something darkened here, is clearly proved by the fact that blue arises in this region). Through something darkened—through the blue colour, in effect—you look at something light, namely at the cylinder-of-light coming towards you. Through what is dark you look at what is light; here therefore you should be seeing yellow or yellowish-red—in a word, yellow and red,—as in fact you do. Likewise the red colour below is proof that here is a region irradiated with light. For as I said just now, the light here over-whelms the dark. Thus as you look in this direction, however bright the cylinder of light itself may be, you still see it through an irradiation of light, in relation to which it is dark. Below, therefore, you are looking at dark through light and you will see blue or bluish-red. You need but express the primal phenomenon,—it tells you what you actually see. Your eye is here encountered by what you would be seeing in the other instance. Here for example is the blue and you are looking through it; therefore the light appears reddish. At the bottom edge you have a region that is lighted up. However light the cylinder of light may be, you see it through a space that is lit up. Thus you are seeing something darker through an illumined space and so you see it blue. It is the polarity that matters.

For the phenomenon we studied first—that on the screen—you may use the name “objective” colours if you wish to speak in learned terms. This other one—the one you see in looking through the prism—will then be called the “subjective” spectrum. The “subjective” spectrum appears as an inversion of the “objective”.

Concerning all these phenomena there has been much intellectual speculation, my dear Friends, in modern time. The phenomena have not merely been observed and stated purely as phenomena, as we have been endeavouring to do. There has been ever so much speculation about them; indeed, beginning with the famous Newton, Science has gone to the utter-most extremes in speculation. Newton, having first seen and been impressed by this colour-spectrum, began to speculate as to the nature of light. Here is the prism, said Newton; we let the white light in. The colours are already there in the white light; the prism conjures them forth and now they line up in formation. I have then dismembered the white light into its constituents. Newton now imagined that to every colour corresponds a kind of substance, so that seven colours altogether are contained as specific substances in the light. Passing the light through the prism is to Newton like a kind of chemical analysis, whereby the light is separated into seven distinct substances. He even tried to imagine which of the substances emit relatively larger corpuscles—tiny spheres or pellets—and which smaller. According to this conception the Sun sends us its light, we let it into the room through a circular opening and it goes through in a cylinder of light. This light however consists of ever so many corpuscles—tiny little bodies. Striking the surface of the prism they are diverted from their original course. Eventually they bombard the screen. There then these tiny cannon-balls impinge. The smaller ones fly farther up, the larger ones remain farther down. The smallest are the violet, the largest are the red. So then the large are separated from the small.

This idea that there is a substance or that there are a number of substances flying through space was seriously shaken before long by other physicists—Huyghens, Young and others,—until at last the physicists said to themselves: The theory of little corpuscular cannon-balls starting from somewhere, projected through a refracting medium or not as the case may be, arriving at the screen and there producing a picture, or again finding their way into the eye and giving rise in us to the phenomenon of red, etc.,—this will not do after all. They were eventually driven to this conclusion by an experiment of Fresnel's, towards which some preliminary work had however been done before, by the Jesuit Grimaldi among others.

Fresnel's experiment shook the corpuscular theory very considerably. His experiments are indeed most interesting, and we must try to get a clear idea of what is really happening when experiments are set up in the way he did. I beg you now, pay very careful attention to the pure facts; we want to study such a phenomenon quite exactly. Suppose I have two mirrors and a source of light—a flame for instance, shedding its light from here (Figure IVd). If I then put up a screen—say, here—I shall get pictures by means of the one mirror and also pictures by means of the other mirror. Such is the distribution you are to assume; I draw it in cross-section. Here are two looking-glasses—plane mirrors, set at a very small angle to one another,—here is a source of light, I will call it L, and here a screen. The light is reflected and falls on to the screen; so then I can illumine the screen with the reflected light. For if I let the light strike here, with the help of this mirror I can illumine this part of the screen, making it lighter here than in the surrounding region. Now I have here a second mirror, by which the light is reflected a little differently. Part of the cone of light, as reflected from here below (from the second mirror) on to the screen, still falls into the upper part. The inclination of the two mirrors is such that the screen is lighted up both by reflection from the upper mirror and by reflection from the lower. It will then be as though the screen were being illumined from two different places. Now suppose a physicist, witnessing this experiment, were thinking in Newton's way. He would argue: There is the source of light. It bombards the first mirror, hurling its little cannon-balls in this direction. After recoiling from the mirror they reach the screen and light it up. Meanwhile, the others are recoiling from the lower mirror, for many of them go in that direction also. It will be very much lighter on the screen when there are two mirrors than when there is only one. Therefore if I remove the second mirror the screen will surely be less illumined by reflected light than when the two mirrors are there. So would our physicist argue, although admittedly one rather devastating thought might occur to him, for surely while these little bodies are going on their way after reflection, the others are on their downward journey (see the figure). Why then the latter should not hit the former and drive them from their course, is difficult to see. Nay, altogether, in the textbooks you will find the prettiest accounts of what is happening according to the wave-theory, but while these things are calculated very neatly, one cannot but reflect that no one ever figures out, when one wave rushes criss-cross through the other, how can this simply pass unnoticed?

Now let us try to grasp what happens in reality in this experiment. Suppose that this is the one stream of light. It is thrown by reflection across here, but now the other stream of light arrives here and encounters it,—the phenomenon is undeniable. The two disturb each other. The one wants to rush on; the other gets in the way and, in consequence, extinguishes the light coming from the other side. In rushing through it extinguishes the light. Here therefore on the screen we do not get a lighting-up but in reality darkness is reflected across here. So we here get an element of darkness (Figure IVe). But now all this is not at rest,—it is in constant movement. What has here been disturbed, goes on. Here, so to speak, a hole has arisen in the light. The light rushed through; a hole was made, appearing dark. And as an outcome of this “hole”, the next body-of-light will go through all the more easily and alongside the darkness you will have a patch of light so much the lighter. The next thing to happen, one step further on, is that once more a little cylinder of light from above impinges on a light place, again extinguishes the latter, and so evokes another element of darkness. And as the darkness in its turn has thus moved on another step, here once again the light is able to get through more easily. We get the pattern of a lattice, moving on from step to step. Turn by turn, the light from above can get through and extinguishes the other, producing darkness, once again, and this moves on from step to step. Here then we must obtain an alternation of light and dark, because the upper light goes through the lower and in so doing makes a lattice work.

This is what I was asking you most thoroughly to think of; you should be able to follow in your thought, how such a lattice arises. You will have alternating patches of light and dark, inasmuch as light here rushes into light. When one light rushes into another the light is cancelled—turned to darkness. The fact that such a lattice arises is to be explained by the particular arrangement we have made with these two mirrors. The velocity of light—nay, altogether what arises here by way of differences in velocity of light,—is not of great significance. What I am trying to make clear is what here arises within the light itself by means of this apparatus, so that a lattice-work is reflected—light, dark, light, dark, and so on.

Now yonder physicist—Fresnel himself, in fact—argued as follows: If light is a streaming of tiny corpuscular bodies, it goes without saying that the more bodies are being hurled in a particular direction, the lighter it must grow there,—or else one would have to assume that the one corpuscle eats up the other! The simple theory of corpuscular emanation will not explain this phenomenon of alternating light and dark. We have just seen how it is really to be explained. But it did not occur to the physicists to take the pure phenomenon as such, which is what one should do. Instead, and by analogy with certain other phenomena, they set to work to explain it in a materialistic way. Bombarding little balls of matter would no longer do. Therefore they said: Let us assume, not that the light is in itself a stream of fine substances, but that it is a movement in a very fine substantial medium—the “ether”. It is a movement in the ether. And, to begin with, they imagined that light is propagated through the ether in the same way as sound is through air (Euler for instance thought of it thus). If I call forth a sound, the sound is propagated through the air in such a way that if this is the place where the sound is evoked, the air in the immediate neighbourhood is, to begin with, compressed. Compressed air arises here. Now the compressed air presses in its turn on the adjoining air. It expands, momentarily producing in this neighbourhood a layer of attenuated air. Through these successions of compression and expansion, known as waves, we imagine sound to spread. To begin with, they assumed that waves of this kind are also kindled in the ether. However, there were phenomena at variance with this idea; so then they said to themselves: Light is indeed an undulatory movement, but the waves are of a different kind from those of sound. In sound there is compression here, then comes attenuation, and all this moves on. Such waves are “longitudinal”. For light, this notion will not do. In light, the particles of ether must be moving at right angles to the direction in which the light is being propagated. When, therefore, what we call a “ray of light” is rushing through the air—with a velocity, you will recall, of 300,000 kilometres a second—the tiny particles will always be vibrating at right angles to the direction in which the light is rushing. When this vibration gets into our eye, we perceive it.

Apply this to Fresnel's experiment: we get the following idea. The movement of the light is, once again, a vibration at right angles to the direction in which the light is propagated. This ray, going towards the lower one of the two mirrors, is vibrating, say, in this way and impinges here. As I said before, the fact that wave-movements in many directions will be going criss-cross through each other, is disregarded. According to the physicists who think along these lines, they will in no way disturb each other. Here however, at the screen in this experiment, they do; or again, they reinforce each other. In effect, what will happen here? When the train of waves arrives here, it may well be that the one infinitesimal particle with its perpendicular vibrations happens to be vibrating downward at the very moment when the other is vibrating upward. Then they will cancel each other out and darkness will arise at this place. Or if the two are vibrating upward at the same moment, light will arise. Thus they explain, by the vibrations of infinitesimal particles, what we were explaining just now by the light itself. I was saying that we here get alternations of light patches and dark. The so-called wave-theory of light explains them on the assumption that light is a wave-movement in the other [ether?]. If the infinitesimal particles are vibrating so as to reinforce each other, a lighter patch will arise; if contrary to one another, we get a darker patch.

You must realize what a great difference there is between taking the phenomena purely as they are—setting them forth, following them with our understanding, remaining amid the phenomena themselves—and on the other hand adding to them our own inventions. This movement of the ether is after all a pure invention. Having once invented such a notion we can of course make calculations about it, but that affords no proof that it is really there. All that is purely kinematical or phoronomical in these conceptions are merely thought by us, and so is all the arithmetic. You see from this example: our fundamental way of thought requires us so to explain the phenomena that they themselves be the eventual explanation; they must contain their own explanation. Please set great store by this. Mere spun-out theories and theorizings are to be rejected. You can explain what you like by adding things out of the blue, of which man has no knowledge. Of course the waves might conceivably be there, and it might be that the one swings upward when the other downward so that they cancel each other out. But they have all been invented! What is there however without question is this lattice,—this we see fully reflected. It is to the light itself that we must look, if we desire a genuine and not a spurious, explanation.

Now I was saying just now: when the one light goes through the other, or enters into any kind of relation to it, it may well have a dimming or even extinguishing effect upon the other, just as the effect of the prism is to dim the light. This is again brought out in the following experiment, which we shall actually be doing, I will now make a drawing of it. We may have what I shewed you yesterday—a spectrum extending from violet to red—engendered directly by the Sun. But we can also generate the spectrum in another way. Instead of letting the Sun shine through an opening in the wall, we make a solid body glow with heat,—incandescent (Figure IVf). When we have by and by got it white-hot, it will also give us such a spectrum. It does not matter if we get the spectrum from the Sun or from an incandescent body.

Now we can also generate a spectrum in a somewhat different way (Figure IVg). Suppose this is a prism and this a sodium flame—a flame in which the metal sodium is volatilizing. The sodium is turned to gas; it burns and volatilizes. We make a spectrum of the sodium as it volatilizes. Then a peculiar thing happens. Making a spectrum, not from the Sun or from a glowing solid body but from a glowing gas, we find one place in the spectrum strongly developed. For sodium light it is in the yellow. Here will be red, orange, yellow, you will remember. It is the yellow that is most strongly developed in the spectrum of sodium. The rest of the spectrum is stunted—hardly there at all. All this—from violet to yellow and then again from yellow to red—is stunted. We seem to get a very narrow bright yellow strip, or as is generally said, a yellow line. Mark well, the yellow line also arises inasmuch as it is part of an entire spectrum, only the rest of the spectrum in this case is stunted, atrophied as it were.

From diverse bodies we can make spectra of this kind appearing not as a proper spectrum but in the form of bright, luminous lines. From this you see that vice-versa, if we do not know what is in a flame and we make a spectrum of it, we can conclude, if we get this yellow spectrum for example, that there is sodium in the flame. So we can recognize which of the metals is there.

But the remarkable thing comes about when we combine the two experiments. We generate this cylinder of light and the spectrum of it, while at the same time we interpose the sodium flame, so that the glowing sodium somehow unites with the cylinder of light (Figure IVh). What happens then is very like what I was shewing you in Fresnel's experiment. In the resulting spectrum you might expect the yellow to appear extra strong, since it is there to begin with and now the yellow of the sodium flame is added to it. But this is not what happens. On the contrary, the yellow of the sodium flame extinguishes the other

yellow and you get a dark place here. Precisely where you would expect a lighter part you get a darker. Why is it so? It simply depends on the intensity of force that is brought to bear. If the sodium light arising here were selfless enough to let the kindred yellow light arising here it would have to extinguish itself in so doing. This it does not do; it puts itself in the way at the very place where the yellow should be coming through. It is simply there, and though it is yellow itself, the effect of it is not to intensify but to extinguish. As a real active force, it puts itself in the way, even as an indifferent obstacle might do; it gets in the way. This yellow part of the spectrum is extinguished and a black strip is brought about instead. From this again you see, we need only bear in mind what is actually there. The flowing light itself gives us the explanation.

These are the things which I would have you note. A physicist explaining things in Newton's way would naturally argue: If I here have a piece of white—say, a luminous strip—and I look at it through the prism, it appears to me in such a way that I get a spectrum: red, orange, yellow, green, blue, dark blue, violet (Figure IVi). Goethe said: Well, at a pinch, that might do. If Nature really is like that—if she has made the light composite—we might well assume that with the help of the prism this light gets analyzed into its several parts. Good and well; but now the very same people who say the light consists of these seven colours—so that the seven colours are parts or constituents of the light—these same people allege that darkness is just nothing,—is the mere absence of light. Yet if I leave a strip black in the midst of white—if I have simple white paper with a black strip in the middle and look at this through a prism,—then too I find I get a rainbow, only the colours are now in a different order (Figure IVk),—mauve in the middle, and on the one side merging into greenish-blue. I get a band of colours in a different order. On the analysis-theory I ought now to say: then the black too is analyzable and I should thus be admitting that darkness is more than the mere absence of light. The darkness too would have to be analyzable and would consist of seven colours. This, that he saw the black band too in seven colours, only in a different order,—this was what put Goethe off. And this again shews us how needful it is simply to take the phenomena as we find them.

My dear Friends,

Today I will begin by shewing, as well as may be with our limited resources, the experiment of which we spoke last time. You will remember: when an incandescent solid body spreads its light and we let this light go through a prism, we get a “spectrum”, a luminous picture, very like what we should get from the Sun, (compare Figure IVf), towards the end of Lecture IV). Now we can also obtain a luminous picture with the light that spreads from a glowing gas; however this picture only shews one or more single lines of light or little bands of light at different places, according to the substance used, (Figure IVg). The rest of the spectrum is stunted, so to speak. By very careful experiment, it is true, we should perceive that everything luminous gives a complete spectrum—expending all the way from red to violet, to say no more. Suppose for example we make a spectrum with glowing sodium gas: in the midst of a very feeble spectrum there is at one place a far more intense yellow line, making the rest seem even darker by contrast. Sodium is therefore often spoken of as giving only this yellow line.

And now we come to the remarkable fact, which, although not unknown before, was brought to light above all in 1859 by the famous experiment of Kirchhoff and Bunsen. If we arrange things so that the source of light generating the continuous spectrum and the one generating, say, the sodium line, can take effect as it were simultaneously, the sodium line will be found to act like an untransparent body. It gets in the way of the quality of light which would be appearing at this place (i.e. in the yellow) of the spectrum. It blots it out, so that we get a black line here in place of yellow, (Figure IVh). Simply to state the fact, this then is what we have to say: For the yellow of the spectrum, another yellow (the strength of which must be at least equal to the strength of light that is just being developed at this place of the spectrum) acts like an opaque body. As you will presently see, the elements we are compiling will pave the way to an understanding also of this phenomenon. In the first place however we must get hold of the pure facts.

We will now shew you, as well as we are able, that this dark line does really appear in the spectrum when we interpose the glowing sodium. We have not been able to arrange the experiment so as to project the spectrum on to a screen. Instead we will observe the spectrum by looking straight into it with our eyes. For it is possible to see the spectrum in this way too; it then appears displaced downward instead of upward, moreover the colours are reversed. We have already discussed, why it is that the colours appear in this way when we simply look through the prism.

By means of this apparatus, we here generate the cylinder of light; we let it go through here, and, looking into it, we see it thus refracted. (The experiment was shewn to everyone in turn).

To use the short remaining time—we shall now have to consider the relation of colours to what we call “bodies”. As a transition to this problem looking for the relations between the colours and what we commonly call “bodies”—I will however also shew the following experiment. You now see the complete spectrum projected on to the screen. Into the path of the cylinder of light I place a trough in which there is a little iodine dissolved in carbon disulphide. Note how the spectrum is changed. When I put into the path of the cylinder of light the solution of iodine in carbon disulphide, this light is extinguished. You see the spectrum clearly divided into two portions; the middle part is blotted out. You only see the violet on the one side, the reddish-yellow on the other. In that I cause the light to go through this solution—iodine in carbon disulphide—you see the complete spectrum divided into two portions; you only see the two poles on either hand.

It has grown late and I shall now only have time for a for a few matters of principle. Concerning the relation of the colours to the bodies we see around us (all of which are somehow coloured in the last resort), the point will be explained how it comes about that they appear coloured at all. How comes it in effect that the material bodies have this relation to the light? How do they, simply by dint of their material existence so to speak, develop such relation to the light that one body looks red, another blue, and so on. It is no doubt simplest to say: When colourless sunlight—according to the physicists, a gathering of all the colours—falls on a body that looks red, this is due to the body's swallowing all the other colours and only throwing back the red. With like simplicity we can explain why another body appears blue. It swallows the remaining colours and throws back the blue alone. We on the other hand have to eschew these speculative explanations and to approach the fact in question—namely the way we see what we call “coloured bodies”—by means of the pure facts. Fact upon fact in proper sequence will then at last enable us in time to “catch”—as it were, to close in upon—this very complex phenomenon.

The following will lead us on the way. Even in the 17th Century, we may remember, when alchemy was still pursued to some extent, they spoke of so-called “phosphores” or light-bearers. This is what they meant:—A Bologna cobbler, to take one example, was doing some alchemical experiments with a kind of Heavy Spar (Barytes). He made of it what was then called “Bologna stone”. When he exposed this to the light, a strange phenomenon occurred. After exposure the stone went on shining for a time, emitting a certain coloured light. The Bologna stone had acquired a relation to the light, which it expressed by being luminous still after exposure—after the light had been removed. Stones of this kind were then investigated in many ways and were called “phosphores”, If you come across the word “phosphor” or “phosphorus” in the literature of that time, you need not take it to mean what is called “Phosphorus” today; it refers to phosphorescent bodies of this kind—bearers of light, i.e. phos-phores.

However, even this phenomenon of after-luminescence—phosphor escence—is not the simplest. Another phenomenon is really the simple one. If you take ordinary paraffin oil and look through it towards a light, the oil appears slightly yellow. If on the other hand you place yourself so as to let the light pass through the oil while you look at it from behind, the oil will seem to be shining with a bluish light—only so long, however, as the light impinges on it. The same experiment can be made with a variety of other bodies. It is most interesting if you make a solution of plant green—chlorophyll (Figure Va). Look towards the light through the solution and it appears green. But if you take your stand to some extent behind it—if this (Figure Va) is the solution and this the light going through it, while you look from behind to where the light goes through—the chlorophyll shines back with a red or reddish light, just as the paraffin shone blue.

There are many bodies with this property. They shine in a different way when, so to speak, they of themselves send the light back—when they have somehow come into relation to the light, changing it through their own nature—than when the light goes through them as through a transparent body. Look at the chlorophyll from behind: we see—so to speak—what the light has been doing in the chlorophyll; we see the mutual relation between the light and the chlorophyll. When in this way a body shines with one kind of light while illumined by another kind of light, we call the phenomenon Fluorescence. And, we may say: what in effect is Phosphorescence? It is a Fluorescence that lasts longer. For it is Fluorescence when the chlorophyll, for instance, shines with a reddish light so long as it is exposed to light. When there is Phosphorescence on the other hand, as with the Bologna stone, we can take the light away and the thing still goes on shining for a time. It thus retains the property of shining with a coloured light,—a property the chlorophyll does not retain. So you have two stages. The one is Fluorescence: we make a body coloured so long as we illumine it. The second is Phosphorescence: we cause a body to remain coloured still for a certain time after illumination. And now there is a third stage: the body, as an outcome of whatever it is that the light does with it, appears with a lasting colour. We have this sequence: Fluorescence, Phosphorescence, Colouredness-of-bodies.

Thus we have placed the phenomena, in a manner of speaking, side by side. What we must try to do is to approach the phenomena rightly with our thinking, our forming of ideas. There is another fundamental idea which you will need to get hold of today, for we shall afterwards want to relate it to all these other things. Please, once again, only think quite exactly of what I shall bring forward. Think as precisely as you can. I will remind you again (as once before in these lectures) of the formula for a velocity, say \(v\). A velocity is expressed, as you know, in dividing \(s\), the distance which the mobile object passes through, by the time \(t\). This therefore is the formula:

Now the opinion prevails that what is actually given in real Nature in such a case is the distance \(s\) the body passes through, and the time \(t\) it takes to do it. We are supposed to be dividing the real distance \(s\) by the real time \(t\), to get the velocity \(v\), which as a rule is not regarded as being quite so real but more as a kind of function, an outcome of the division sum. Thus the prevailing opinion. And yet in Nature it is not so. Of the three magnitudes—velocity, space and time,—velocity is the only one that has reality. What is really there in the world outside us is the velocity; the \(s\) and \(t\) we only get by splitting up the given totality, the \(v\), into two abstract entities. We only arrive at these on the basis of the velocity, which is really there. This then, to some extent, is our procedure. We see a so-called “body” flowing through space with a certain velocity. That it has this velocity, is the one real thing about it. But now we set to work and think. We no longer envisage the quick totality, the quickly moving body; instead, we think in terms of two abstractions. We dismember, what is really one, into two abstractions. Because there is a velocity, there is a distance moved through. This distance we envisage in the first place, and in the second place we envisage the time it takes to do it. From the velocity, the one thing actually there, we by our thinking process have sundered space and time; yet the space in question is not there at all save as an outcome of the velocity, nor for that matter is the time. The space and time, compared to this real thing which we denote as \(v\), are no realities at all, they are abstractions which we ourselves derive from the velocity. We shall not come to terms with outer reality, my dear Friends, till we are thoroughly clear on this point. We in our process of conception have first created this duality of space and time. The real thing we have outside us is the velocity and that alone; as to the “space” and “time”, we ourselves have first created them by virtue of the two abstractions into which—if you like to put it so—the velocity can fall apart for us.

From the velocity, in effect, we can separate ourselves, while from the space and time we cannot; they are within our perceiving,—in our perceiving activity. With space and time we are one. Much is implied in what I am now saying. With space and time we are one. Think of it well. We are not one with the velocity that is there outside us, but we are one with space and time. Nor should we, without more ado, ascribe to external bodies what we ourselves are one with; we should only use it to gain a proper idea of these external bodies. All we should say is that through space and time, with which we ourselves are very intimately united, we learn to know and understand the real velocity. We should not say “The body moves through such and such a distance”; we ought only to say: “The body has a velocity”. Nor should we say, “The body takes so much time to do it,” but once again only this: “The body has a velocity”. By means of space and time we only measure the velocity. The space and time are our own instruments. They are bound to us,—that is the essential thing. Here once again you see the sharp dividing line between what is generally called “subjective”—here, space and time—and the “objective” thing—here, the velocity. It will be good, my dear Friends, if you will bring this home to yourselves very clearly; the truth will then dawn upon you more and more: \(v\) is not merely the quotient of \(s\) and \(t\). Numerically, it is true, \(v\) is expressed by the quotient of \(s\) and \(t\). What I express by this number \(v\) is however a reality in its own right—a reality of which the essence is, to have velocity.

What I have here shewn you with regard to space and time—namely that they are inseparable from us and we ought not in thought to separate ourselves from them—is also true of another thing. But, my dear Friends (if I may say this in passing), people are still too much obsessed with the old Konigsberg habit, by which I mean, the Kantian idea. The “Konigsberg” habit must be got rid of, or else it might be thought that I myself have here been talking “Konigsberg”, as if to say “Space and Time are within us.” But that is not what I am saying. I say that in perceiving the reality outside us the—velocity—we make use of space and time for our perception. In effect, space and time are at once in us and outside us. The point is that we unite with space and time, while we do not unite with the velocity. The latter whizzes past us. This is quite different from the Kantian idea.

Now once again: what I have said of space and time is also true of something else. Even as we are united by space and time with the objective reality, while we first have to look for the velocity, so in like manner, we are in one and the same element with the so-called bodies whenever we behold them by means of light. We ought not to ascribe objectivity to light any more than to space and time. We swim in space and time just as the bodies swim in it with their velocities. So too we swim in the light, just as the bodies swim in the light. Light is an element common to us and the things outside us—the so-called bodies. You may imagine therefore: Say you have gradually filled the dark room with light, the space becomes filled with something—call it \(x\), if you will—something in which you are and in which the things outside you are. It is a common element in which both you, and that which is outside you, swim. But we have still to ask: How do we manage to swim in light? We obviously cannot swim in it with what we ordinarily call our body. We do however swirl in it with our etheric body. You will never understand what light is without going into these realities. We with our etheric body swim in the light (or, if you will, you may say, in the light-ether; the word does not matter in this connection). Once again therefore: With our etheric body we are swimming in the light.

Now in the course of these lectures we have seen how colours arise—and that in many ways—in and about the light itself. In the most manifold ways, colours arise in and about the light; so also they arise, or they subsist, in the so-called bodies. We see the ghostly, spectral colours so to speak,—those that arise and vanish within the light itself. For if I only cast a spectrum here it is indeed like seeing spectres; it hovers, fleeting, in space. Such colours therefore we behold, in and about the light.

In the light, I said just now, we swim with our etheric body. How then do we relate ourselves to the fleeting colours? We are in them with our astral body; it is none other than this. We are united with the colours with our astral body. You have no alternative, my dear Friends but to realise that when and wheresoever you see colours, with your astrality you are united with them. If you would reach any genuine knowledge you have no alternative, but must say to yourselves: The light remains invisible to us; we swim in it. Here it is as with space and time; we ought not to call them objective, for we ourselves are swimming in them. So too we should regard the light as an element common to us and to the things outside us; whilst in the colours we have to recognize something that can only make its appearance inasmuch as we through our astral body come into relation to what the light is doing there.

Assume now that in this space \(ABCD\) you have in some way brought about a phenomenon of colour—say, a spectrum. I mean now, a phenomenon that takes its course purely within the light. You must refer it to an astral relation to the light. But you may also have the phenomenon of colour in the form of a coloured surface. This therefore—from \(A\) to \(C,\) say—may be appearing to you as a coloured body, a red body for example. We say, then, \(AC\) is red. You look towards the surface of the body, and, to begin with, you will imagine rather crudely. Beneath the surface it is red, through and through. This time, you see, the case is different. Here too you have an astral relation; but from the astral relation you enter into with the colour in this instance you are separated by the bodily surface. Be sure you understand this rightly! In the one instance you see colours in the light—spectral colours. There you have astral relations of a direct kind; nothing is interposed between you and the colours. When on the other hand you see the colours of bodily objects, something is interposed between you and your astral body, and through this something you none the less entertain astral relations to what we call “bodily colours”. Please take these things to heart and think them through. For they are basic concepts—very important ones—which we shall need to elaborate. Only on these lines shall we achieve the necessary fundamental concepts for a truer Physics.

One more thing I would say in conclusion. What I am trying to present in these lectures is not what you can get from the first text-book you may purchase. Nor is it what you can get by reading Goethe's Theory of Colour. It is intended to be, what you will find in neither of the two, and what will help you make the spiritual link between them. We are not credulous believers in the Physics of today, nor need we be of Goethe. It was in 1832 that Goethe died. What we are seeking is not a Goetheanism of the year 1832 but one of 1919,—further evolved and developed. What I have said just now for instance—this of the astral relation—please think it through as thoroughly as you are able.

My dear Friends,

In our last lecture we were going into certain matters of principle which I will now try to explain more fully. For if we start from the experiences we can gain in the realm of light, it will also help us observe and understand other natural phenomena which we shall presently be studying. I will therefore begin today with these more theoretical reflections and put off the experimental part until tomorrow. We must determine still more exactly the method of our procedure. It is the task of Science to discern and truly to set forth the facts in the phenomena of Nature. Problems of method which this task involves can best be illustrated in the realm of Light.

Men began studying the phenomena of light in rather recent times, historically speaking. Nay, the whole way of thinking about the phenomena of Physics, presented in the schools today, reaches hardly any farther back than the 16th century. The way men thought of such phenomena before the 16th century was radically different. Today at school we get so saturated with the present way of thought that if you have been through this kind of schooling it is extremely difficult for you to find your way back to the pure facts. You must first cultivate the habit of feeling the pure facts as such; please do not take my words in a too trivial meaning. You have to learn to sense the facts, and this takes time and trouble.

I will now take my start from a particular instance wherein we may compare the way of thought prevailing in the schools today with that which can be gained by following the facts straightforwardly. Suppose this were a plate of glass, seen in cross-section (Figure VIa). Through it you look at a luminous object. As I am drawing it diagrammatically, let me represent the latter simply by a light circle. Cast your mind back to what you learned in your school days. What did they teach you of the phenomenon you see when you observe the luminous object,—with your eye, say, here—looking through the glass? You were no doubt told that rays of light proceed from the luminous object. (We are imagining the eye to be looking in this particular direction,—see the Figure). Rays, you were told, proceed from the shining object. In the direction of the “ray” I am now drawing, the light was said to penetrate from a more tenuous into a denser medium. Simply by looking through the glass and comparing what you see with what you saw before the plate of glass was there, you do indeed perceive the thing displaced. It appears at a different place than without the glass. Now this is said to be due to the light being “refracted”. This is how they are wont to put it:—When the light passes from a more tenuous into a denser medium, to find the direction in which the light will be refracted, you must draw the so-called “normal at the point of incidence”. If the light went on its way without being hindered by a denser medium, it would go on in this direction. But, they now say, the light is “refracted”—in this case, towards the normal, i.e. towards the perpendicular to the glass surface at the point of incidence. Now it goes out again,—out of the glass. (All this is said, you will remember, in tracing how the “ray of light” is seen through the denser medium.) Here then again, at the point of exit from the glass, you will have to erect the normal. If the light went straight on it would go thus: but at this second surface it is again refracted—this time, away from the normal—refracted just enough to make it go on parallel to its original direction. And now the eye, looking as it is from here, is said to produce the final direction of the ray of light and thus to project the luminous object so much the higher up. This then is what we are asked to assume, if we be looking through such a plate of glass. Here, to begin with, the light impinges on the plate, then it is twice refracted—once towards the normal, a second time away from the normal. Then, inasmuch as the eye has the inner faculty to do so (.... or is it to the soul, or to some demon that you ascribe this faculty ....) the light is somehow projected out into space. It is projected moreover to a position different from where it would appear if we were not seeing it through a refracting medium;—so they describe the process.

The following should be observed to begin with, in this connection. Say we are looking at anything at all through the same denser medium, and we now try to discriminate, however delicately, between the darker and lighter portions of what we see. Not only the lighter parts, the darker too will appear shifted upward. The entire complex we are looking at is found to be displaced. Please take this well into account. Here is a darker part bordering on a lighter. The dark is shifted upward, and since one end of it is lighter we see this shifted too. Placing before us any such complex, consisting of a darker and a lighter part, we must admit the lighter part is displaced simply as the upper boundary of the darker. Instead, they speak in such a way as to abstract the one light patch from all the rest that is there. Mostly they speak as though the light patch alone were suffering displacement. Surely this is wrong. For even if I fix my gaze on this one patch of light, it is not true that it alone is shifted upward. The part below it, which I am treating as if it were just nothing when I describe it thus, is shifted upward too. In point of fact, what is displaced in these optical phenomena can never be thus abstractly confined. If therefore I repeat Newton's experiment—I let into the room a cone of light which then gets diverted by the prism—it simply is not true that the cone of light is diverted all alone. Whatever the cone of light is bordering on—above it and below—is diverted too. I really ought never to speak of rays of light or anything of that kind, but only of luminous pictures or spaces-of-light being diverted. In a particular instance I may perhaps want to refer to some isolated light, but even then I still ought not to speak of it in such a way as to build my whole theory of the phenomenon upon it. I still ought to speak in such a way as to refer at the same time to all that borders on the light. Only if we think in this way can we begin to feel what is really going on when the phenomena of colour comes into being before our eyes. Otherwise our very habit of thought begets the impression that in some way the colours spring from the light alone. For from the very outset we have it settled in our mind that the one and only reality we are dealing with is the light. Yet, what we have before us in reality is never simply light as such; it is always something light, bordered on one side or other by darkness. And if the lighter part—the space it occupies—is shifted, the darker part is shifted too. But now, what is this “dark”? You must take the dark seriously,—take it as something real. (The errors that have crept into modern Physics since about the 16th century were only able to creep in because these things were not observed spiritually at the same time. Only the semblance, as appearing to the outer senses, was taken note of; then, to explain this outer semblance, all kinds of theoretical inventions were added to it). You certainly will not deny that when you look at light the light is sometimes more and sometimes less intense. There can be stronger light and less strong. The point is now to understand: How is this light, which may be stronger or weaker related to darkness? The ordinary physicist of today thinks there is stronger light and less strong; he will admit every degree of intensity of light, but he will only admit one darkness—darkness which is simply there when there is no light. There is, as it were, only one way of being black. Yet as untrue as it would be to say that there is only one kind of lightness, just as untrue is it to say that there is only one kind of darkness. It is as one-sided as it would be to declare: “I know four men. One of them owns £25, another £50; he therefore owns more than the other. The third of them is £25 in debt, the fourth is £50 in debt. Yet why should I take note of any difference in their case? It is precisely the same; both are in debt. I will by all means distinguish between more and less property, but not between different degrees of debt. Debt is debt and that is all there is to it.” You see the fallacy at once in this example, for you know very well that the effect of being £25 in debt is less than that of being £50 in debt. But in the case of darkness this is how people think: Of light there are different degrees; darkness is simply darkness. It is this failure to progress to a qualitative way of thinking, which very largely prevents our discovering the bridge between the soul-and-spirit on the one hand, and the bodily realm on the other. When a space is filled with light it is always filled with light of a certain intensity; so likewise, when a space is filled with darkness, it is filled with darkness of a certain intensity. We must proceed from the notion of a merely abstract space to the kind of space that is not abstract but is in some specific way positively filled with light or negatively filled with darkness. Thus we may be confronting a space that is filled with light and we shall call it “qualitatively positive”. Or we may be confronting a space that is filled with darkness and we shall judge it “qualitatively negative” with respect to the realm of light. Moreover both to the one and to the other we shall be able to ascribe a certain degree of intensity, a certain strength. Now we may ask: How does the positive filling of space differ for our perception from the negative? As to the positive, we need only remember what it is like when we awaken from sleep and are surrounded by light,—how we unite our subjective experience with the light that floods and surges all around us. We need only compare this sensation with what we feel when surrounded by darkness, and we shall find—I beg you to take note of this very precisely—we shall find that for pure feeling and sensation there is an essential difference between being given up to a light-filled space and to a darkness-filled space. We must approach these things with the help of some comparison. Truly, we may compare the feeling we have, when given up to a light-filled space, with a kind of in-drawing of the light. It is as though our soul, our inner being, were to be sucking the light in. We feel a kind of enrichment when in a light-filled space. We draw the light into ourselves. How is it then with darkness? We have precisely the opposite feeling. We feel the darkness sucking at us. It sucks us out, we have to give away,—we have to give something of ourselves to the darkness. Thus we may say: the effect of light upon us is to communicate, to give; whilst the effect of darkness is to withdraw, to suck at us and take away. So too must we distinguish between the lighter and the darker colours. The light ones have a quality of coming towards us and imparting something to us; the dark colours on the other hand have a quality of drawing on us, sucking at us, making us give of ourselves. So at long last we are led to say: Something in our outer world communicates itself to us when we are under the influence of light; something is taken from us, we are somehow sucked out, when under the influence of darkness.

There is indeed another occasion in our life, when—as I said once before during these lectures—we are somehow sucked-out as to our consciousness; namely when we fall asleep. Consciousness ceases. It is a very similar phenomenon, like a cessation of consciousness, when from the lighter colours we draw near the darker ones, the blue and violet. And if you will recall what I said a few days ago about the relation of our life of soul to mass,—how we are put to sleep by mass, how it sucks-out our consciousness,—you will feel something very like this in the absorption of our consciousness by darkness. So then you will discern the deep inner kinship between the condition space is in when filled with darkness and on the other hand the filling of space which we call matter, which is expressed in “mass”.

Thus we shall have to seek the transition from the phenomena of light to the phenomena of material existence. We have indeed paved the way, in that we first looked for the fleeting phenomena of light—phosphorescence and fluorescence—and then the firm and fast phenomena of light, the enduring colours. We cannot treat all these things separately; rather let us begin by setting out the whole complex of these facts together.

Now we shall also need to recognize the following, When we are in a light-filled space we do in a way unite with this light-filled space. Something in us swings out into the light-filled space and unites with it. But we need only reflect a little on the facts and we shall recognize an immense difference between the way we thus unite with the light-flooded spaces of our immediate environment and on the other hand the way we become united with the warmth-conditions of our environment,—for with these too, as human beings, we do somehow unite.

We do indeed share very much in the condition of our environment as regards warmth; and as we do so, here once again we feel a kind of polarity prevailing, namely the polarity of warm and cold. Yet we must needs perceive an essential difference between the way we feel ourselves within the warmth-condition of our environment and the way we feel ourselves within the light-condition of our environment. Physics, since the 16th century, has quite lost hold of this difference. The open-mindedness to distinguish how we join with our environment in the experience of light upon the one hand and warmth upon the other has been completely lost; nay, the deliberate tendency has been, somehow to blur and wipe away such differences as these. Suppose however that you face the difference, quite obviously given in point of fact, between the way we experience and share in the conditions of our environment as regards warmth and light respectively. Then in the last resort you will be bound to recognize that the distinction is: we share in the warmth-conditions of our environment with our physical body and in the light-conditions, as we said just now, with our etheric body. This in effect—this proneness to confuse what we become aware of through our ether-body and what we become aware of through our physical body—has been the bane of Physics since the 16th century. In course of time all things have thus been blurred. Our scientists have lost the faculty of stating facts straightforwardly and directly. This has been so especially since Newton's influence came to be dominant, as it still is to a great extent today. There have indeed been individuals who have attempted from time to time to draw attention to the straightforward facts simply as they present themselves. Goethe of course was doing it all through, and Kirchhoff among others tried to do it in more theoretic ways. On the whole however, scientists have lost the faculty of focusing attention purely and simply on the given facts. The fact for instance that material bodies in the neighbourhood of other material bodies will under given conditions fall towards them, has been conceived entirely in Newton's sense, being attributed from the very outset to a force proceeding from the one and affecting the other body—a “force of gravity”. Yet ponder how you will, you will never be able to include among the given facts what is understood by the term “force of gravity”. If a stone falls to the Earth the fact is simply that it draws nearer to the Earth. We see it now at one place, now at another, now at a third and so on. If you then say “The Earth attracts the stone” you in your thoughts are adding something to the given fact; you are no longer purely and simply stating the phenomenon.

People have grown ever more unaccustomed to state the phenomena purely, yet upon this all depends. For if we do not state the phenomena purely and simply, but proceed at once to thought-out explanations, we can find manifold explanations of one and the same phenomenon. Suppose for example you have two heavenly bodies. You may then say: These two heavenly bodies attract one another,—send some mysterious force out into space and so attract each other (Figure VIb). But you need not say this. You can also say: “Here is the one body, here is the other, and here (Figure VIc) are a lot of other, tiny bodies—particles of ether, it may be—all around and in between the two heavenly bodies. The tiny particles are bombarding the two big ones—bombarding here, there and on all sides;—the ones between, as they fly hither and thither, bombard them too. Now the total area of attack will be bigger outside than in between. In the resultant therefore, there will be less bombardment inside than outside; hence the two bodies will approach each other. They are, in fact, driven towards each other by the difference between the number of impacts they receive in the space between them and outside them.”

There have in fact been people who have explained the force of gravity simply by saying: It is a force acting at a distance and attracts the bodies towards each other. Others have said that that is nonsense; according to them it is unthinkable for any force to act at a distance. They then invite us to assume that space is filled with “ether”, and to assume this bombardment too. The masses then are, so to speak, for ever being sprayed towards each other. To add to these explanations there are no doubt many others. It is a classical example of how they fail to look at the real phenomenon but at once add their thought-out explanations.

Now what is at the bottom of it all? This tendency to add to the phenomena in thought—to add all manner of unknown agencies and fancied energies, presumed to be doing this or that—saves one the need of doing something else. Needless to say, the impacts in the theory of Figure VIc have been gratuitously added, just as the forces acting at a distance have been in the other theory. These adventitious theories, however, relieve one of the need of making one fundamental assumption, from which the people of today seem to be very much averse. For in effect, if these are two independent heavenly bodies and they approach each other, or show that it is in their nature to approach each other, we cannot but look for some underlying reason why they do so; there must be some inner reason. Now it is simpler to add in thought some unknown forces than to admit that there is also another way, namely no longer to think of the heavenly bodies as independent of each other. If for example I put my hand to my forehead, I shall not dream of saying that my forehead “attracts” my hand, but I shall say: It is an inner deed done by the underlying soul-and-spirit. My hand is not independent of my forehead; they are not really separate entities. I shall regard the phenomenon rightly only by recognising myself as a single whole. I should have no reality in mind if I were to say: There is a head, there are two arms and hands, there is a trunk, there are two legs. There would be nothing complete in that; I only have something complete in mind if I describe the whole human body as a single entity,—if I describe the different items so that they belong together. My task is not merely to describe what I see; I have to ponder the reality of what I see. The mere fact that I see a thing does not make it real.

Often I have made the following remark,—for I have had to indicate these things in other lectures too. Take a crystal cube of rock-salt. It is in some respect a totality. (Everything will be so in some respect). The crystal cube can exist by virtue of what it is within the compass of its six faces. But if you look at a rose, cut from the shrub it grew on, this rose is no totality. It cannot, like the cube of rock-salt, exist by virtue of all that is contained within it. The rose can only have existence by being of the rose-bush. The cut rose therefore, though you can see it just as you can see the cube of rock-salt, is a real abstraction; you may not call it a reality by itself.

The implications of this, my dear Friends, are far-reaching. Namely, for every phenomenon, we must examine to what extent it is a reality in itself, or a mere section of some larger whole. If you consider Sun and Moon, or Sun and Earth, each by itself, you may of course invent and add to them a force of gravity, just as you might invent a force of gravity by means of which my forehead would attract my right hand. But in considering Sun and Earth and Moon thus separately, the things you have in mind are not totalities; they are but parts and members of the whole planetary system.

This then is the essential thing; observe to what extent a thing is whole, or but a section of a whole. How many errors arise by considering to be a whole what is in fact only a partial phenomenon within a larger whole! By thus considering only the partial phenomena and then inventing energies to add to these, our scientists have saved themselves the need of contemplating the inherent life of the planetary system. The tendency has been, first to regard as wholes those things in Nature which are only parts, and by mere theories then to construe the effects which arise in fact between them. This therefore, to sum up, is the essential point: For all that meets us in Nature we have to ask: What is the whole to which this thing belongs? Or is it in itself a whole? Even then, in the last resort, we shall find that things are wholes only in certain respects. Even the crystal cube of rock-salt is a totality only in some respect; it too cannot exist save at certain temperatures and under other requisite conditions. Given some other temperature, it could no longer be. Our need is therefore to give up looking at Nature in the fragmentary way which is so prevalent in our time.

Indeed it was only by looking at Nature in this fragmentary way that Science since the 16th century conceived this strange idea of universal, inorganic, lifeless Nature. There is indeed no such thing, just as in this sense there is no such thing as your bony system without your blood. Just as your bony system could only come into being by, as it were, crystallizing out of your living organism as a whole, so too this so-called inorganic Nature cannot exist without the whole of Nature—soul and Spirit-Nature—that underlies it. Lifeless Nature is the bony system, abstracted from Nature as a whole. It is impossible to study it alone, as they began doing ever since the 16th century and as is done in Newtonian Physics to this day.

It was the trend of Newtonian Physics to make as neat as possible an extract of this so-called inorganic Nature, treating it then as something self-contained. This “inorganic Nature” only exists however in the machines which we ourselves piece together from the parts of Nature. And here we come to something radically different. What we are wont to call “inorganic” in Nature herself, is placed in the totality of Nature in quite another way. The only really inorganic things are our machines, and even these are only so insofar as they are pieced together from sundry forces of Nature by ourselves. Only the “put-togetherness” of them is inorganic. Whatever else we may call inorganic only exists by abstraction. From this abstraction however present-day Physics has arisen. This Physics is an outcome of abstraction; it thinks that what it has abstracted is the real thing, and on this assumption sets out to explain whatever comes within its purview

As against this, the only thing we can legitimately do is to form our ideas and concepts in direct connection with what is given to us from the outer world—the details of the sense-world. Now there is one realm of phenomena for which a very convenient fact is indeed given. If you strike a bell and have some light and very mobile device in the immediate neighbourhood, you will be able to demonstrate that the particles of the sounding bell are vibrating. Or with a pipe playing a note, you will be able to show that the air inside it is vibrating. For the phenomena of sound and tone therefore, you have the demonstrable movement of the particles of air or of the bell; so you will ascertain that there is a connection between the vibrations executed by a body or by the air and our perceptions of tone or sound. For this field of phenomena it is quite patent: vibrations are going on around us when we hear sounds. We can say to ourselves that unless the air in our environment is vibrating we shall not hear any sounds. There is a genuine connection—and we shall speak of it again tomorrow—between the sounds and the vibrations of the air.

Now if we want to proceed very abstractly we may argue: “We perceive sound through our organs of hearing. The vibrations of the air beat on our organ of hearing, and when they do so we perceive the sound. Now the eye too is a sense-organ and through it we perceive the colours; so we may say: here something similar must be at work. Some kind of vibration must be beating on the eye. But we soon see it cannot be the air. So then it is the ether.” By a pure play of analogies one is thus led to the idea: When the air beats upon our ear and we have the sensation of a sound, there is an inner connection between the vibrating air and our sensation; so in like manner, when the hypothetical ether with its vibrations beats upon our eye, a sensation of light is produced by means of this vibrating ether. And as to how the ether should be vibrating: this they endeavour to ascertain by means of such phenomena as we have seen in our experiments during these lectures. Thus they think out an universal ether and try to calculate what they suppose must be going on in this ethereal ocean. Their calculations relate to an unknown entity which cannot of course be perceived but can at most be assumed theoretically.

Even the very trifling experiments we have been able to make will have revealed the extreme complication of what is going on in the world of light. Till the more recent developments set in, our physicists assumed that behind—or, should we rather say, within—all thus that lives and finds expression in light and colour there is the vibrating ether, a tenuous elastic substance. And since the laws of impact and recoil of elastic bodies are not so difficult to get to know, they could compute what these vibrating little cobolds must be up to in the ether. They only had to regard them as little elastic bodies,—imagining the ether as an inherently elastic substance. So they could even devise explanations of the phenomena we have been showing,—e.g. the forming of the spectrum. The explanation is that the different kinds of ether-vibrations are dispersed by the prism; these different kinds of vibrations then appear to us as different colours. By calculation one may even explain from the elasticity of the ether the extinction of the sodium line for example, which we perceived in our experiment the day before yesterday.

In more recent times however, other phenomena have been discovered. Thus we can make a spectrum, in which we either create or extinguish the sodium line (i.e., in the latter case, we generate the black sodium line). If then in addition we bring an electro-magnet to bear upon the cylinder of light in a certain way, the electro-magnet affects the phenomenon of light. The sodium line is extinguished in its old place and for example two other lines arise, purely by the effect of the electricity with which magnetic effects are always somehow associated. Here, then, what is described as “electric forces” proves to be not without effect upon those processes which we behold as phenomena of light and behind which one had supposed the mere elastic ether to be working. Such discoveries of the effect of electricity on the phenomena of light now led to the assumption that there must be some kinship between the phenomena of light and those of magnetism and electricity.

Thus in more recent times the old theories were rather shaken. Before these mutual effects had been perceived, one could lean back and rest content. Now one was forced to admit that the two realms must have to do with each other. As a result, very many physicists now include what radiates in the form of light among the electro-magnetic effects. They think it is really electro-magnetic rays passing through space.

Now think a moment what has happened. The scientists had been assuming that they knew what underlies the phenomena of light and colour: namely, undulations in the elastic ether. Now that they learned of the interaction between light and electricity, they feel obliged to regard, what is vibrating there, as electricity raying through space. Mark well what has taken place. First it is light and colour which they desire to explain, and they attribute them to the vibrating ether. Ether-vibrations are moving through space. They think they know what light is in reality,—it is vibrations in the elastic ether. Then comes the moment when they have to say: What we regarded as vibrations of the elastic ether are really vibrations of electro-magnetic force. They know still better now, what light is, than they did before. It is electro-magnetic streams of force. Only they do not know what these are! Such is the pretty round they have been. First a hypothesis is set up: something belonging to the sense-world is explained by an unknown super-sensible, the vibrating ether. Then by and by they are driven to refer this super-sensible once more to something of the sense-world, yet at the same time to confess that they do not know what the latter is. It is a highly interesting journey that has here been made; from the hypothetical search for an unknown to the explanation of this unknown by yet another unknown.

The physicist Kirchhoff was rather shattered and more or less admitted: It will be not at all easy for Physics if these more recent phenomena really oblige us no longer to believe in the undulating ether. And when Helmholtz got to know of the phenomenon, he said: Very well, we shall have to regard light as a kind of electro-magnetic radiation. It only means that we shall now have to explain these radiations themselves as vibrations in the elastic ether. In the last resort we shall get back to these, he said.

The essence of the matter is that a genuine phenomenon of undulation—namely the vibrating of the air when we perceive sounds—was transferred by pure analogy into a realm where in point of fact the whole assumption is hypothetical.

I had to go into these matters of principle today, to give the necessary background. In quick succession we will now go through the most important aspects of those phenomena which we still want to consider. In our remaining hours I propose to discuss the phenomena of sound, and those of warmth, and of electro-magnetics; also whatever explanations may emerge from these for our main theme—the phenomena of optics.

My dear Friends,

We will begin today with an experiment bearing upon our studies of the theory of colour. As I have said before, all I can give you in this Course can only be improvised and aphoristic. Hence too I cannot keep to the conventional categories of the Physics textbooks,—in saying which I do not mean to imply that it would be better if I did. In the last resort I wish to lead you to a certain kind of insight into Science, and you must look on all that I bring forward in the meantime as a kind of preparation. We are not advancing in the usual straight line. We try to gather up the diverse phenomena we need, forming a circle as it were,—then to move forward from the circumference towards the centre.

You have seen that wherever colours arise there is a working-together of light and darkness. What we now have to do is to observe as many phenomena as we can before we try to theorize. We want to form a true conception of what underlies this interplay of light and darkness. Today I will begin by shewing you the phenomenon of coloured shadows, as they are called.

Here are two candles (Figure VIIa),—candles as sources of light—and an upright rod which will throw shadows on this screen. You see two shadows, without perceptible colour. You only need to take a good look at what is here before you, you will be bound to say: the shadow you are seeing on the right is the one thrown by the left-hand source of light. It is produced, in that the light from this source is hidden by the rod. Likewise the shadow on the left arises where the light from the right-hand source is covered. Relatively dark spaces are created,—that is all. Where the shadow is, is simply a dark space. Moreover, looking at the surface of the screen apart from the two bands of shadow, you will agree it is illumined by both sources of light. Now I will colour the one (the left-hand) light. I make the light go through a plate of coloured glass, so that this one of the lights is now coloured—that is, darkened to some extent. As a result, you will see that the shadow of the rod, due to this left-hand source of light—the one which I am darkening to red—this shadow on the right becomes green. It becomes green just as a purely white background does when you look sharply for example at a small red surface for a time, then turn your eye away and look straight at the white. You then see green where you formerly saw red, though there is nothing there. You yourself, as it were, see the green colour on to the white surface. In such a case, you are seeing the green surface as an after-image in time of the red which you were seeing just before, when you exposed your eye to the red surface that was actually there. And so in this case: when I darken the source of light to red, you see the shadow green. What was mere darkness before, you now see green. And now I darken the same source of light to green,—the shadow becomes red. And when I darken it to blue, an orange shadow is produced. If I should darken it to violet, it would give yellow.

And now consider please the following phenomenon; it is most important, therefore I mention it once more. Say in a room you have a red cushion with a white crochet cover, through the rhombic-patterned apertures of which the red of the cushion shines through. You look at the red rhombic pattern and then look away to the white. On the white ground you see the same lattice-work in green. Of course it isn't there, but your own eye is active and makes an after-effect, which, as you focus on the white, generates the green, “subjective” images, as one is wont to call them.

Goethe was familiar with this phenomenon, and also knew that of the coloured shadows. I darken this source of light and get green, said Goethe to himself, and he went on to describe it somewhat as follows: When I darken this source of light, the white screen as a whole shines red. I am not really seeing the white screen; what I see is a reddish-shining colour. In fact I see the screen more or less red. And as an outcome—as with the cushion mentioned just now—I with my own eye generate the contrasting colour. There is no real green here. I only see the green incidentally, because the screen as a whole now has a reddish colour.

However, this idea of Goethe's is mistaken, as you may readily convince yourselves. Take a little tube and look through it, so that you only see the shadow; you will still see it green. You no longer see what is around it, you only see the green which is objectively there at the place you look at. You can convince yourself by this experiment that the green really is objective. It remains green, hence the phenomenon cannot be one of mere contrast but is objective. We cannot now provide for everyone to see it, but as the proverb says, durch zweier Zeugen Mund wird alle Wahrheit kund—two witnesses will always tell the truth. I will produce the phenomenon and you must now look through on to the green strip. It stays green, does it not? So with the other colour: if I engendered red by means of green, it would stay red. Goethe in this instance was mistaken, and as the error is incorporated in his Theory of Colour it must of course be rectified.¹

Now to begin with, my dear Friends, along with all the other phenomena which we have studied, I want you to take note of the pure fact we have just demonstrated. In the one case we get a grey, a bit of darkness, a mere shadow. In the other case we permeate the shadow, so to speak, with colour. The light and darkness then work together in a different way. We note that by darkening the light with red the objective phenomenon of the green is called forth. Now side by side with this, I also drew your attention to what appears, as is generally said, “subjectively”. We have then, in the one case, what would be called an “objective” phenomenon, the green that stays there on the screen; though not a permanently fixed colour, it stays as long as we create the requisite conditions. Whilst in the other case we have something, as it were, subjectively conditioned by our eye alone. Goethe calls the green colour that appears to me when I have been exposing my eye for a time to red, the colour or coloured after-image that is evoked or “required” (gefordert),—called forth by reaction.

Now there is one thing we must insist on in this connection. The “subjective, objective” distinction, between the colour that is temporarily fixed here and the colour that seems only to be called forth as an after-image by the eye, has no foundation in any real fact. When I am seeing red through my eyes, as at this moment, you know there is all the physical apparatus we were describing a few days ago; the vitreous body, the lens, the aqueous humour between the lens and the cornea,—a highly differentiated physical apparatus. This physical apparatus, mingling light and darkness as it does in the most varied ways with one another, is in no other relation to the objectively existent ether than all the apparatus we have here set up—the screen, the rod and so on. The only difference is that in the ^one case the whole apparatus is my eye; I see an objective phenomenon through my own eye. It is the same objective phenomenon which I see here, only that this one stays. By dint of looking at the red, my eye will subsequently react with the “required” colour—to use Goethe's term,—the eye, according to its own conditions, being gradually restored to its neutral state. But the real process by means of which I see the green when I see it thus, as we are wont to say, “subjectively”—through the eye alone,—is in no way different from what it is when I fix the colour “objectively” as in this experiment.

Therefore I said in an earlier lecture: You, your subjective being, do not live in such a way that the ether is there vibrating outside of you and the effect of it then finds expression in your experience of colour. No, you yourself are swimming in the ether—you are one with it. It is but an incidental difference, whether you become at one with the ether through this apparatus out here or through a process that goes on in your own eye. There is no real nor essential difference between the green image engendered spatially by the red darkening of the light, and the green afterimage, appearing afterwards only in point of time. Looked at objectively there is no tangible difference, save that the process is spatial in the one case and temporal in the other. That is the one essential difference. A sensible and thoughtful contemplation of these things will lead you no longer to look for the contrast, “subjective and objective” as we generally call it, in the false direction in which modern Science generally tries to see it. You will then see it for what it really is. In the one case we have rigged-up an apparatus to engender colour while our eye stays neutral—neutral as to the way the colours are here produced—and is thus able to enter into and unite with what is here. In the other case the eye itself is the physical apparatus. What difference does it make, whether the necessary apparatus is out there, or in your frontal cavity? We are not outside the things, then first projecting the phenomena we see out into space. We with our being are in the things; moreover we are in them even more fully when we go on from certain kinds of physical phenomena to others. No open-minded person, examining the phenomena of colour in all their aspects, can in the long run fail to admit that we are in them—not, it is true, with our ordinary body, but certainly with our etheric body and thereby also with the astral part of our being.

And now let us descend from Light to Warmth. Warmth too we perceive as a condition of our environment which gains significance for us whenever we are exposed to it. We shall soon see, however, that as between the perception of light and the perception of warmth there is a very significant difference. You can localize the perception of light clearly and accurately in the physical apparatus of the eye, the objective significance of which I have been stressing. But if you ask yourself in all seriousness, “How shall I now compare the relation I am in to light with the relation I am in to warmth?”, you will have to answer, “While my relation to the light is in a way localized—localized by my eye at a particular place in my body,—this is not so for warmth. For warmth the whole of me is, so to speak, the sense-organ. For warmth, the whole of me is what my eye is for the light”. We cannot therefore speak of the perception of warmth in the same localized sense as of the perception of light. Moreover, precisely in realizing this we may also become aware of something more.

What are we really perceiving when we come into relation to the warmth-condition of our surroundings? We must admit, we have a very distinct perception of the fact that we are swimming in the warmth-element of our environment. And yet, what is it of us that is swimming? Please answer for yourselves the question: What is it that is swimming when you are swimming in the warmth of your environment? Take then the following experiment. Fill a bucket with water just warm enough for you to feel it lukewarm. Put both your hands in—not for long, only to test it. Then put your left hand in water as hot as you can bear and your right hand in water as cold as you can bear. Then put both hands quickly back again into the lukewarm water. You will find the lukewarm water seeming very warm to your right hand and very cold to your left. Your left hand, having become hot, perceives as cold what your right hand, having become cold, perceives as warmth. Before, you felt the same lukewarmness on either side. What is it then? It is your own warmth that is swimming there. Your own warmth makes you feel the difference between itself and your environment. What is it therefore, once again,—what is it of you that is swimming in the warmth-element of your environment? It is your own state-of-warmth, brought about by your own organic process. Far from this being an unconscious thing, your consciousness indwells it. Inside your skin you are living in this warmth, and according to the state of this your own warmth you converse—communicate and come to terms—with the element of warmth in your environment, wherein your own bodily warmth is swimming. It is your warmth-organism which really swims in the warmth of your environment.—If you think these things through, you will come nearer the real processes of Nature—far nearer than by what is given you in modern Physics, abstracted as it is from all reality.

Now let us go still farther down. We experience our own state-of-warmth by swimming with it in our environment-of-warmth. When we are warmer than our environment we feel the latter as if it were drawing, sucking at us; when we are colder we feel as though it were imparting something to us. But this grows different again when we consider how we are living in yet another element. Once more then: we have the faculty of living in what really underlies the light; we swim in the element of light. Then, in the way we have been explaining, we swim in the element of warmth. But we are also able to swim in the element of air, which of course we always have within us. We human beings, after all, are to a very small extent solid bodies. More than 90% of us is just a column of water, and—what matters most in this connection—the water in us is a kind of intermediary between the airy and the solid state. Now we can also experience ourselves quite consciously in the airy element, just as we can in the element of warmth. Our consciousness descends effectively into the airy element. Even as it enters into the element of light and into the element of warmth, so too it enters into the element of air. Here again, it can “converse”, it can communicate and come to terms with what is taking place in our environment of air. It is precisely this “conversation” which finds expression in the phenomena of sound or tone. You see from this: we must distinguish between different levels in our consciousness. One level of our consciousness is the one we live with in the element of light, inasmuch as we ourselves partake in this element. Quite another level of our consciousness is the one we live with in the element of warmth, inasmuch as we ourselves, once more, are partaking in it. And yet another level of our consciousness is the one we live with in the element of air, inasmuch as we ourselves partake also in this. Our consciousness is indeed able to dive down into the gaseous or airy element. Then are we living in the airy element of our environment and are thus able to perceive the phenomena of sound and of musical tone. Even as we ourselves with our own consciousness have to partake in the phenomena of light so that we swim in the light-phenomena of our environment; and as we have to partake in the element of warmth so that we swim also in this; so too must we partake in the element of air. We must ourselves have something of the airy element within us in a differentiated form so that we may be able to perceive—when, say, a pipe, a drum or a violin is resounding—the differentiated airy element outside us. In this respect, my dear Friends, our bodily nature is indeed of the greatest interest even to outward appearance. There is our breathing process: we breathe-in the air and breathe it out again. When we breathe-out the air we push our diaphragm upward. This involves a relief of tension, a relaxation, for the whole of our organic system beneath the diaphragm. In that we raise the diaphragm as we breathe-out and thus relieve the organic system beneath the diaphragm, the cerebrospinal fluid in which the brain is swimming is driven downward. Here now the cerebrospinal fluid is none other than a somewhat condensed modification, so to speak, of the air, for it is really the out-breathed air which brings about the process. When I breathe-in again, the cerebrospinal fluid is driven upward. I, through my breathing, am forever living in this rhythmic, downward-and-upward, upward-and-downward undulation of the cerebrospinal fluid, which is quite clearly an image of my whole breathing process. In that my bodily organism partakes in these oscillations of the breathing process, there is an inner differentiation, enabling me to perceive and experience the airy element in consciousness. Indeed by virtue of this process, of which admittedly I have been giving only a rather crude description, I am forever living in a rhythm-of-life which both in origin and in its further course consists in an inner differentiation of the air.

In that you breathe and bring about—not of course so crudely but in a manifold and differentiated way—this upward and downward oscillation of the rhythmic forces, there is produced within you what may itself be described as an organism of vibrations, highly complicated, forever coming into being and passing away again. It is this inner organism of vibrations which in our ear we bring to bear upon what sounds towards us from without when, for example, the string of a musical instrument gives out a note. We make the one impinge upon the other. And just as when you plunge your hand into the lukewarm water you perceive the state-of-warmth of your own hand by the difference between the warmth of your hand and the warmth of the water, so too do you perceive the tone or sound by the impact and interaction of your own inner, wondrously constructed musical instrument with the sound or tone that comes to manifestation in the air outside you. The ear is in a way the bridge, by which your own inner “lyre of Apollo” finds its relation, in ever-balancing and compensating interplay, with the differentiated airy movement that comes to you from without. Such, in reality is hearing. The real process of hearing—hearing of the differentiated sound or tone—is, as you see, very far removed from the abstraction commonly presented. Something, they say, is going on in the space outside, this then affects my ear, and the effect upon my ear is perceived in some way as an effect on my subjective being. For the “subjective being” is at long last referred to—described in some kind of demonology—or rather, not described at all. We shall not get any further if we do not try to think out clearly, what is the underlying notion in this customary presentation. You simply cannot think these notions through to their conclusion, for what this school of Physics never does is to go simply into the given facts.

Thus in effect we have three stages in man's relation to the outer world—I will describe them as the stage of Light, the stage of Warmth, and that of Tone or Sound. There is however a remarkable fact in this connection. Look open-mindedly at your relation to the element of light—your swimming in the element of light—and you will have to admit: It is only with your etheric body that you can live in what is there going on in the outer world. Not so when you are living in the element of warmth. You really live in the warmth-element of your environment with your whole bodily nature. Having thus contemplated how you live in light and warmth, look farther down—think how you live in the element of tone and sound—and you will recognize: Here you yourself are functioning as an airy body. You, as a living organism of air, live in the manifoldly formed and differentiated outer air. It is no longer the ether; it is external physical matter, namely air. Our living in the warmth-element is then a very significant border-line. Our life in the element of warmth is for our consciousness a kind of midway level—a niveau. You recognize it very clearly in the simple fact that for pure feeling and sensation you are scarcely able to distinguish outer warmth from inner warmth. Your life in the light-element however lies above this level:—

For light, you ascend as it were into a higher, into an etheric sphere, therein to live with your consciousness. On the other hand you go beneath this level, beneath this niveau, when in perceiving tone or sound you as a man-of-air converse and come to terms with the surrounding air. While upon this niveau itself (in the perceiving of warmth) you come to terms with the outer world in a comparatively simple way.

Now bring together what I have just been shewing with what I told you before out of Anatomy and Physiology. Then you will have to conceive the eye as the physical apparatus, to begin with. Indeed the farther outward you go, the more physical do you find the eye to be; the farther in you go, the more is it permeated with vitality. We therefore have in us a localized organ—the eye—with which to lift ourselves above a certain level or niveau. Upon this actual niveau we live as it were on equal terms with our environment; with our own warmth we meet the warmth of our environment and perceive the difference, whatever it may be. Here we have no such specialized organ as the eye; the whole of us, we ourselves in some way, become the sense-organ. And we dive down beneath this level or niveau when functioning as airy man,—when we converse and come to terms with the differentiated outer air. Here once again the “conversation” becomes localized—localized namely in this “lyre of Apollo”, in this rhythmic play of our whole organism, of which the rhythmic play of our spinal fluid is but the image and the outcome. Here then again we have something localized—only beneath the niveau this time, whilst in the eye it is above this midway level.

The Psychology of our time is, as you see, in an even sorrier position than the Physiology and Physics, and we can scarcely blame our physicists if they speak so unrealistically of what is there in the outer world, since they get so little help from the psychologists. The latter, truth to tell, have been only too well disciplined by the Churches, which have claimed all the knowledge of the soul and Spirit for their own domain. Very obediently the psychologists restrict their study to the external apparatus, calling this external apparatus “Man”. They speak no doubt of soul and mind, or even Spirit, but in mere words, mere sounding phrases, until Psychology becomes at last a mere collection of words. For in their books they never tell us what we are to understand by soul and mind and Spirit,—how we should conceive them. So then the physicists come to imagine that the light is there at work quite outside us; this light affects the human eye. The eye somehow responds; at any rate it receives an impression. This then becomes subjective inner experience. Now comes the veriest tangle of confused ideas. The physicists allege it to be much the same as to the other sense-organs. They follow what they learn from the psychologists. In text-books of Psychology you will generally find a chapter on the Science of the Senses, as though such a thing as “sense” or “sense-organ” in general existed. But if you put it to the test: study the eye,—it is completely different from the ear. The one indeed lies above and the other beneath the “niveau” which we explained just now. In their whole form and structure, eye and ear prove to be totally diverse organs. This surely is significant and should be borne in mind. Today now we will go thus far; please think it over in the meantime. Taking our start from this, we will tomorrow speak of the science of sound and tone, whence you will then be able to go on into the other realms of Physics.

There is however one more thing I want to demonstrate today. It is among the great achievements of modern Physics; it is in truth a very great achievement. You know that if you merely rub a surface with your finger—exerting pressure, using some force as you do so,—the surface will get warm. By this exertion you have generated warmth. So too by calling forth out-and-out mechanical processes in the objective world external to yourself, you can engender warmth. Now as a basis for tomorrow's lecture, we have rigged up this apparatus. If you were now to look and read the thermometer inside, you would find it a little over 16° C. The vessel contains water. Immersed in the body of water is a kind of drum or flywheel which we now bring into quick rotation, thus doing mechanical work, whirling the portions of the water all about, stirring it thoroughly. After a time we shall look at the thermometer again and you will see that it has risen. By dint of purely mechanical work the water will have gained in warmth. That is to say, warmth is produced by mechanical work. It was especially Julius Robert Mayer who drew attention to this fact, which was then worked out more arithmetically. Mayer himself derived from it the so-called “mechanical equivalent of warmth” (or of heat). Had they gone on in the same spirit in which he began, they would have said no more than that a certain number, a certain figure expresses the relation which can be measured when warmth is produced by dint of mechanical work or vice-versa. But they exploited the discovery in metaphysical fashion. Namely they argued: If then there is this constant ratio between the mechanical work expended and the warmth produced, the warmth or heat is simply the work transformed. Transformed, if you please!—where in reality all that they had before them was the numerical expression of the relation between the two.

• 1. After some careful experiments on a later occasion, Dr. Steiner admitted that there is an error here. (See the Translator's Note on this passage.) He also recommended chemical and photographic researches to show the real nature of coloured shadows.

My dear Friends,

The way of speaking about sound and tone which you will find in the customary description of modern Physics may be said to date back to the 15th century at the earliest. By such examples you will most readily confirm what I so often speak of more generally in Spiritual Science. Namely, before that turning-point in time, man's whole way of thinking was very different from what it then became.

The way we speak of the phenomena of sound and tone in the scholastic system of modern Physics came about only gradually. What first caught their attention was the velocity with which sound is propagated. To a first approximation it is not difficult to find what may be interpreted as the speed of propagation of sound. If a gun is fired at some distance from you, you see the flash of light in the distance and hear the report some time later, just as you hear the thunder after you see the lightning. If you neglect that there is such a thing as a velocity of light, you may then call the time that elapses between your perception of the impression of light and your perception of the sound, the time the sound has taken to go the corresponding distance. So you can calculate how quickly the sound advances in air—how far it goes, say, in a second—and you get something like a “velocity of propagation of sound”.

This was one of the earliest things to which men became attentive in this domain. They also became attentive to the so-called phenomena of resonance—sympathetic vibration. Leonardo da Vinci was among the first. If for example you twang a violin-string or the like, and another string attuned to it—or even quite a different object that happens to be so attuned—is there in the same room, the other will begin vibrating too. The Jesuits especially took up the study of these things. In the 17th century much was done for the science of sound or tone by the Jesuit Mersenne, who made important researches on what is called the ‘pitch’ of a musical note. A note contains three elements. It has first a certain intensity; secondly a certain pitch; thirdly a certain quality or colouring of sound. The problem is to ascertain what corresponds to the pitch,—to ascertain this from the point of view which, as I said, has gradually been adopted in modern time,—adopted most of all, perhaps, in this branch of Science. I have already drawn your attention to the fact which can indeed easily be ascertained. Whenever we perceive a sound or a musical note, there is always some oscillatory phenomenon that underlies it—or, shall we rather say, accompanies, runs parallel to it. The usual experiments can easily be reproduced, to demonstrate this oscillatory character of air or other bodies. Here is a tuning-fork with a point attached, which as it moves can make a mark in the layer of soot, deposited on this glass plate. We need not actually do all these experiments, but if we did strike the tuning-fork to begin with, the picture on the glass plate would reveal that this tuning-fork is executing regular movements. These forms of movement are naturally conveyed to the air and we may therefore say that when we hear any sounding body the air between it and us is in movement. Indeed we bring the air itself directly into movement in the instruments called pipes.

Now scientists have gradually discovered what kind of movement it is. It takes place in ‘longitudinal’ waves, as they are called. This too can be directly demonstrated. We kindle a note in this metallic tube, which we connect with another tube full of air, so that the movements of the metallic tube are communicated to this air. If we then put a very light and mobile dust into the tube that is filled with air, the mobility of the tiny spheres of dust enables us to recognize that the sound is propagated just in this way; first there arises a condensation, a densifying of the air; this will beat back again however as soon as the body oscillates the other way. So there arises a thinning-out, a dilution of the air. Then at the next forward beat of the metal the original condensation goes forward; so then dilutions and condensations alternate. We can thus prove by direct experiment that we are dealing with dilutions and condensations of the air. We really need not do all these experiments; they are at hand, if I may say so. What you can get from the text-books is not what I am here to shew.

It is significant indeed, how much was done for these branches of Physics, especially at the beginning of modern time, either by the Jesuits themselves, or else was set on foot by them through all their social connections. Now from this side there was always the strong tendency, above all things, not to enter spiritually into the processes of Nature,—not to penetrate to the spiritual in Nature. The spiritual should be reserved for the religious life. Among the Jesuits it was always looked upon as dangerous to apply to the phenomena of Nature spiritual forms of thought such as we have grown accustomed to through Goethe. They wanted to study Nature in purely materialistic ways,—not to approach Nature with the Spirit. In some respects therefore, the Jesuits were among the first to cultivate the materialistic ideas which are so prevalent today. Historically it is of course well-known, but people fail to reflect that this whole way of thinking, applied to Physics nowadays, is fundamentally a product of the said tendency, characteristically Roman-Catholic as indeed it is.

One of the main things we now have to discover is what happens when we perceive notes of different pitch. How do the external phenomena of vibration, which accompany the note, differ with respect to notes of different pitch? The answer can be shewn by such experiments as we are now about to demonstrate. You see this disc with its rows of holes. We can rotate it rapidly. Herr Stockmeyer will be so kind as to direct a stream of air on to the moving disc. (He did.) You can at once distinguish the different pitch of the two notes. How then did it arise? Nearer the centre of the disc are fewer holes,—40 in fact. When Herr Stockmeyer blew the stream of air on to here, every time it came upon a hole it went through, then in the intervening space it could not get through, then again it could, and so on. Again and again, by the quick motion of the disc, the next hole came where the last had been, and there arose as many beats as there were holes arriving at the place where the stream of air was going. Thus on the inner circle we got 40 beats, but on the outer we got 80 in the same period of time. The beats bring about the wave, the oscillations or vibrations. Thus in the same period of time we have 80 beats, 80 air-waves in the one case and 40 in the other. The note that arises when we have 80 oscillations is twice as high as the note that arises when we have 40. Sundry experiments of this kind shew how the pitch of the note is connected with the number of vibrations arising in the medium in which the sound is propagated.

Please take together what I have just been saying and what was said once before; it will then lead you to the following reflection. A single oscillation of condensation and attenuation gives, as regards the distance it has gone through, what we call the wave-length. If n such waves arise in a second and the length of each wave is s, the whole wave-movement must be advancing n times s in a second. The path, the distance therefore, through which the whole wave-movement advances in a second, is n times s. Now please recall what I said in an earlier lecture. I said that we must carefully distinguish all that is “phoronomical” on the one hand, and on the other hand all that which we do not merely think out in our own inner life of thought but which consists of outer realities. In effect, I said, outward realities can never be merely spatial, or arithmetical (able to be numbered and calculated), nor can they be mere displacements. Velocities on the other hand are outward realities,—they always are. And of course this remains so when we come to sound or tone. Neither the s nor the n can be experienced as an external reality, for the s is merely spatial while the n is a mere number. What is real is inherent in the velocity. The velocity contains the real being, the real entity which we are here describing as ‘sound’ or ‘tone’. If I now divide the velocity into two abstractions, in these abstractions I have no realities; I only have what is abstracted, separated out and divided from it. Such are the wave-lengths—the spatial magnitudes—and also the number n. If on the other hand I want to look at the reality of the sound—at what is real in the world outside myself,—then I must concentrate upon the inner faculty of the sound to have velocity. This then will lead me to a qualitative study of the sound, whereas the way of studying it which we have grown accustomed to in modern Physics is merely quantitative. In the theory of sound, in acoustics especially, we see how modern Physics is always prone to insert what can be stated and recorded in these extraneous, quantitative, spatial and temporal, kinematical and arithmetical forms, in place of the qualitative reality which finds expression simply and solely in a certain faculty of speed, or of velocity.

Today however, people no longer even notice how they sail off into materialistic channels even in the theory of sound. It is so evident, they may well argue, that the sound as such is not there outside us; outside us are only the oscillations. Could anything be clearer?—so they may well contend. There are the waves of condensation and attenuation. Then, when my ear is in the act of “hearing”, what is really there outside me are these condensations and attenuations; that unknown something within me (which the physicist of course need not go into,—it is not his department) therefore transforms the waves into subjective experiences,—transforms the vibrations of the vibrating bodies into the quality that is the ‘sound’ or ‘tone’. In all manner of variations you will find ever the same proposition. Outside us are the vibrations; in us are the effects of the vibrations—effects that are merely subjective. In course of time it has become part of their very flesh and bone, till such results emerge as you find quoted from Robert Hamerling for instance in my Riddles of Philosophy. Having absorbed and accepted the teachings of Physics, Hamerling says at the very outset: What we experience as the report of a gun, is, in the world outside us, no more nor less than a certain violent disturbance of the air. And from this premise Hamerling continues: Whoever does not believe that the sensory impression he experiences is only there in himself while in the world outside him is simply vibrating air or vibrating ether,—let him put down the book which Hamerling is writing; such books are not for him. Robert Hamerling even goes on to say: Whoever thinks that the picture which he obtains of a horse corresponds to an outward reality, understands nothing at all and had better close the book.

Such things, dear Friends, for once deserve to be followed to their logical conclusion. What would become of it if I treated you, who are now sitting here, according to this way of thinking (I do not say method, but way-of-thinking) which physicists have grown accustomed to apply to the phenomena of sound and light? This surely would be the outcome: You, all of you, now sitting here before me,—I only have you here before me through my own impressions, which (if this way of thought be true) are altogether subjective, since my sensations of light and sound are so. None of you are there outside me in the way I see you. Only the oscillations in the air, between you and me, lead me to the oscillations that are there in you, and I am led to the conclusion that all your inner being and life of soul—which, within you and for yourselves, is surely not to be denied—is not there at all. For me, this inner soul of everyone of you who are here seated is only the effect on my own psyche, while for the rest, all that is really there, seated on these benches, are so many heaps of vibrations. If you deny to light and sound the inner life and being which you experience in a seemingly subjective way, it is precisely as it would be if, having you here before me, I looked on all that is before me as merely part of my subjective life, and thus denied to you the experience of inner life and being.

What I have now been saying is indeed so obvious, so trite, that physicists and physiologists will naturally not presume that they could ever fall into such obvious mistakes. And yet they do. The whole distinction that is usually made of the subjective impression (or whatsoever is alleged to be subjective) from the objective process, amounts to this and nothing else. It is of course open to the physicist to be quite candid and to say: I, as physicist, am not proposing to investigate the sound or tone at all; I do not enter into what is qualitative. All I am out to investigate are the external, spatial processes (he will not have to call them “objective processes” for that again would beg the question). All I am out to investigate are the outwardly spatial processes, which of course also go on into my own body. These are the subject-matter of my researches. These I abstract from the totality; what is qualitative is no concern of mine. A man who speaks like this is at least candid and straightforward, only he must not then go on to say that the one is “objective” and the other “subjective”, or that the one is the “effect” of the other. What you experience in your soul,—when I experience it with you it is not the effect upon me of the vibrations of your brain. To see through a thing like that is of untold significance; nothing could be of greater importance for the requirements of the new age, not only in science but in the life of humanity at large.

We ought not to be too reluctant to go into deeper questions when dealing with these matters. How easily it can be argued that the uniquely oscillatory character of sound or tone is evident if only from the fact that if I twang a violin-string a second string in the same room, attuned to the same note, will resound too, this being due to the fact that the intervening medium propagates the accompanying oscillations. Yet we do not understand what is happening in such a case unless we bring it into connection with a more widespread phenomenon. I mean the following for instance,—it has in fact been observed.

You have a pendulum clock; you wind it up and start it. In the same room there is another pendulum clock; it must, admittedly, be of a certain type. This you do not wind up. In favourable circumstances you may observe that the second clock starts of its own accord. We will call this the “mutual sympathy” of phenomena; it can be investigated in a very wide domain. The last phenomenon of this type, still connected to some extent with the outer world, could be examined far more than it generally is, for it is very frequent. Times without number you may have this experience. You are at table with another person and he says something you yourself have just been thinking. You were thinking it but did not say it; he now utters it. It is the sympathetic going-together of events (or complexes of events) in some way attuned to one-another, which is here making itself felt in a highly spiritual realm. We need to recognize the whole range of continuity from the simple resonance of a violin-string which one may still interpret crudely and unspiritually within the sequence of outer material events, to these parallel phenomena which appear so much more spiritual—as when we experience one-another's thoughts.

Now we shall never gain insight into these things unless we have the will to see and understand how man himself is placed into the midst even of so-called physical Nature. A few days ago we were demonstrating and to some extent analyzing the human eye. Today we will do the same with the human ear. As we go inward in the eye, you will remember we come to the vitreous body, which, as we said, still has considerable vitality. Then there is the fluid between the lens and the cornea. As we go inward, we were saying, the eye gets ever more alive and vital, whereas the outer part is increasingly like a piece of physical apparatus. Now we can of course equally well describe the human ear, and in a purely external sense we may aver: Just as the light affects the eye and the optic nerve receives the stimulus, so do the oscillations of sound affect the ear. They go on into the external auditory canal and beat upon the drum which forms the inner end of this canal. Behind the drum are the minute bones or ossicles, called hammer, anvil and stirrup from their appearance. That which arises (speaking in terms of Physics) in the outer world and finds expression in waves of alternate compression and expansion in the air, is transmitted through this peculiar system of ossicles to the inner ear. There is the so-called cochlea, filled with a kind of fluid, and here the auditory nerve has its ending. Before the cochlea we come to the three semicircular canals,—their planes at right angles to each other according to the three dimensions of space. Thus we can imagine the sound penetrating here in the form of air-waves and transmitted by the ossicles until it comes into this fluid. There then it reaches the nerve and so affects the sentient brain. So we should have the eye as one sense-organ, the ear—another. We put them neatly side by side, and—for a further abstraction—we may even elaborate a general physiology of the senses and of sensation.

But it will not seem so simple if you recall what I said recently of the whole rhythm of the ascending and descending cerebrospinal fluid and how it interacts with what is taking place more externally in the outer air. Remember too what I was saying: a thing may look complete and self-contained when outwardly regarded, but we must not therefore take it to be a finished reality, for it need not be so at all. The rose I cut off from the shrub is no reality. It cannot be by itself. It can only come to existence by virtue of its connection with the whole rose-bush. If I think of it as a mere rose by itself, it is in truth an abstraction. I must go on to the totality—to the whole rose-bush at the very least. So too for hearing: the ear alone is no reality, though it is nearly always represented as such in this connection. What is transmitted inward through the ear must first interact in a certain way with the inner rhythm, manifested in the rise and fall of the cerebrospinal fluid. But we have still not reached the end. All this that takes its course in rhythm—and, as it were, includes the brain within its span—is also fundamental, in the real human being, to what appears in quite another part of our body, namely in the larynx and adjoining organs when we are speaking. There is the act of speaking,—its instruments quite obviously inserted into the breathing process, to which the rhythmic rise and fall of the cerebrospinal fluid is also due. In the whole rhythm which arises in you when you breathe, you can therefore insert on the one hand your active speaking and on the other hand your hearing. Then you will have a totality; it only comes to manifestation in a more intelligent or perceptive way in your hearing and in a more volitional way in your speaking. Once more, you only have a totality when you take together the more volitional element pulsating through the larynx and the more sensitive or intelligent that goes through the ear. To separate the ear on the one hand, the larynx on the other, is an abstraction; you have no real totality so long as you separate these two. The two belong together; this is a matter of fact and you need to see it. The physiological physicist or physical physiologist who studies the larynx and the ear apart from one-another proceeds as you would do if you cut up a human being so as to bring him to life instead of seeing things in living interaction.

If we have recognized the facts, this is what we shall see:—Consider what is left of the eye if I first take away the vitreous body and also the whole or at least part of what is here spread out—the retina (Figure IIIf). If I were able to remove all this, what would be left would be the ciliary muscle, the lens and the external liquid—the aqueous humour. What kind of organ would that represent? It would be an organ, my dear Friends, which I could never compare with the ear if I were thinking realistically, but only with the larynx. It is not a metamorphosis of the ear; it is a metamorphosis of the larynx. Only to touch upon the coarsest aspect: just as the muscles of the larynx take hold of the vocal chords, widening or narrowing the aperture between them, so do the ciliary muscles with the lens. The lens is inherently mobile and they take hold of it.

So far I should have separated-out what is larynx-like, so to speak, for the ethereal, even as the larynx is for the air. And if I now reinsert first the retina, then the vitreous body, and then for certain animals the pecten, which man only has etherically, or the falciform process, (blood-bearing organs, continued into the eye in certain lower animals),—this part alone I shall be able truly to relate to the ear. Such things as the expanding portions of the pecten, these I may rightly compare to what expands in the ear,—in the labyrinth and so on. Thus, at one level in the human body I have the eye. In its more inward parts it is a metamorphosed ear, enveloped from without by a metamorphosed larynx. If we take larynx and ear together as a single whole, we have a metamorphosed eye upon another level.

What I have now been pointing out will lead us presently along a most important path. We can have no real knowledge of these things if we relate them falsely to begin with by simply placing eye and ear side by side, whereas in truth the ear can only be compared to the part of the eye behind the lens—the inner and more vital part—while that which reaches farther forward and is more muscular in character must be related to the larynx. This of course makes the theory of metamorphosis more difficult. It is no use looking for metamorphoses in crude, external ways. You must be able to see into the inner dynamic qualities, for these are real.

If it be so however, my dear Friends, we shall no longer be able to conceive as parallel, without more ado, all that goes on in the phenomena of tone and sound on the one hand and on the other hand the phenomena of light. Having begun with the mistaken premise that eye and ear are equally sense-organs, we shall be no less mistaken in our approach to the related phenomena. My seeing in effect is fundamentally different from my hearing. When I am seeing, the same thing happens in my eye as when I hear and speak at the same time. Here, in a higher realm, an activity which can only be compared to the activity of speech accompanies the receptive activity as such—the perceiving, receiving activity of the eye. You will get nowhere in these realms unless you apprehend what is real. For if you once become aware that in the eye two things are welded together which are assigned to seemingly distinct organs of the body in sound or hearing, then you will realize that in seeing, in the eye, we have a kind of monologue,—as when you converse and come to an understanding with yourself. The eye always proceeds as you would do if you were listening intently and every time, to understand what you were hearing, you first repeated it aloud. Such is the eye's activity,—it is as though you were listening to someone and at the same time repeating what you heard, word for word. The other person says, “he writes”, but this does not suffice you. You first repeat aloud, “he writes”,—then and then only is the thing complete. So it is with the eye and the phenomena of light. What comes into our consciousness as an outcome of this whole complex—namely through the fact that we have the more vital, inner part of the eye to begin with—only becomes the full experience of sight, in that we reproduce it in the portion of the eye that corresponds to the larynx and that lies farther forward. Etherically we are talking to ourselves when we are seeing. The eye is engaged in a monologue, and it is wrong to compare the outcome of this monologue—in which the human being's own activity is already contained—with hearing alone, for this is but a single factor of the dual process.

I do believe, dear Friends, that if you work it through for yourselves this will give you much indeed. For it will shew you among other things how far astray materialistic Physics goes and how unreal it becomes in its study of the World, in that it starts by comparing what is not directly comparable—the eye and ear in this instance. It is this purely outward way of study—failing to look and see what are totalities and what are not—which leads away from any spiritual view of Nature. Think for example of what Goethe does at the conclusion of his Theory of Colour, where in the chapter on the “Ethical-Aesthetical Effects of Colour” he evolves the spiritual logically from what is physical. You will never do this if you take your start from the colour-theory of modern Physics.

Now I admit that sound or tone may cause misgivings. Is it not evident that in the outer world mere oscillations are going on when you hear sound? (In some such words it will be stated.) However, ask yourselves another question and then decide whether the very putting of it does not give the answer. Might it not be as follows? Suppose you had a globe or bell-jar, full of air, provided with an aperture and stopcock. Open the stopcock,—nothing will happen if the air inside has the same density as outside. But if there is a vacuum inside, plenty will happen. Air from outside will whistle in and fill the empty space. Will you then say that the air which the globe now contains came into being simply by virtue of what was going on inside the globe? No. You will say: This air has come in from outside, but the empty space—purely to describe the phenomenon as you see it—has somehow sucked it in.

So also when we turn this disc and blow against the holes, we create the conditions for a kind of suction to arise,—this is a true way to describe it. The tone, the sound that will appear when as I work the siren I cause the air to oscillate,—this tone is already in existence, only it is outside of space. It is not yet in space. The conditions for it to enter space are not given until I make them, even as the conditions for the outer air to get into the globe are not given until I make them. The outer air-waves can only be compared to the vacuum inside the globe, and what then grows audible can only be compared to what penetrates from the surrounding space into the vacuum inside when the conditions have been created for this to happen. In essence the air-waves have no more to do with the sound than that, where these waves are, a process of suction is produced to draw the sound from its non-spatial realm into the spatial. Of course the kind of sound, the particular tone that is drawn in, is modified by the kind of air-waves, but so too would it modify what happens in the evacuated globe if I made special-shaped channels in the aperture by which the air is to be drawn in. The air would then expand into the inner space along certain lines, of which an image was there. So have the processes of sound or tone their external image in the observed processes of oscillation.

You see from this, dear Friends, the fundamentals of a true Physical Science, which we aspire to, are not so easy to conceive. It is by no means enough to entertain a few mathematical notions about wave-movements or oscillations. We must make greater demands on the qualitative element in human thinking. If such demands are unfulfilled, we only get once more the picture of the World which is so worshipped in the Physics of today, and which is to reality as is a tissue-paper effigy to a living man.

My dear Friends,

I am sorry these explanations have had to be so improvised and brief, so that they scarcely go beyond mere aphorisms. It is inevitable. All I can do during these days is to give you a few points of view, with the intention of continuing when I am here again, so that in time these explanations may be rounded off, to give you something more complete. Tomorrow I will give a few concluding aspects, also enabling us to throw some light on the educational use of scientific knowledge. Now to prepare for tomorrow, I must today draw your attention to the development of electrical discoveries, beginning no doubt with things that are well-known to you from your school days. This will enable us, in tomorrow's lecture, to gain a more comprehensive view of Physics as a whole.

You know the elementary phenomena of electricity. A rod of glass, or it may be of resin, is made to develop a certain force by rubbing it with some material. The rod becomes, as we say, electrified; it will attract small bodies such as bits of paper. You know too what emerged from a more detailed observation of these phenomena. The forces proceeding from the glass rod, and from the rod of resin or sealing-wax, prove to be diverse. We can rub either rod, so that it gets electrified and will attract bits of paper. If the electrical permeation, brought about with the use of the glass rod, is of one kind, with the resinous rod it proves to be opposite in kind. Using the qualitative descriptions which these phenomena suggest, one speaks of vitreous and resinous electricities respectively; speaking more generally one calls them “positive” and “negative”. The vitreous is then the positive, the resinous the negative.

Now the peculiar thing is that positive electricity always induces and brings negative toward itself in some way. You know the phenomenon from the so-called Leyden Jar. This is a vessel with an electrifiable coating on the outside. Then comes an insulating layer (the substance of the vessel). Inside, there is another coating, connected with a metal rod, ending perhaps in a metallic knob (Figure IXa). If you electrify a metal rod and impart the electricity to the one coating, so that this coating will then evince the characteristic phenomena, say, of positive electricity, the other coating thereby becomes electrified negatively. Then, as you know, you can connect the one coating, imbued with positive, and the other, imbued with negative electricity, so as to bring about a connection of the electrical forces, positive and negative, with one another. You have to make connection so that the one electricity can be conducted out here, where it confronts the other. They confront each other with a certain tension, which they seek to balance out. A spark leaps across from the one to the other. We see how the electrical forces, when thus confronting one another, are in a certain tension, striving to resolve it. No doubt you have often witnessed the experiment.

Here is the Leyden Jar,—but we shall also need a two-pronged conductor to discharge it with. I will now charge it. The charge is not yet strong enough. You see the leaves repelling one another just a little. If we charged this sufficiently, the positive electricity would so induce the negative that if we brought them near enough together with a metallic discharger we should cause a spark to fly across the gap. Now you are also aware that this kind of electrification is called frictional electricity, since the force, whatever it may be, is brought about by friction. And—here again, I am presumably still recalling what you already know—it was only at the turn of the 18th and 19th centuries that they discovered, in addition to this “frictional electricity”, what is called “contact electricity”, thus opening up to modern Physics a domain which has become notably fruitful in the materialistic evolution of this science.

I need only remind you of the main principles. Galvani observed the leg of a frog which was in touch with metal plates and began twitching. He had discovered something of very great significance. He had found two things at once, truth to tell,—two things that should really be distinguished from one-another and are not yet quite properly distinguished, unhappily for Science, to this day. Galvani had discovered what Volta, a little later, was able to describe simply as “contact electricity”, namely the fact that when diverse metals are in contact, and their contact is also mediated by the proper liquids, an interaction arises—an interaction which can find expression in the form of an electric current from the one metal to the other. We have then the electric current, taking place to all appearances purely within the inorganic realm. But we have something else as well, if once again we turn attention to the discovery made by Galvani. We have what may in some sense be described as “physiological electricity”. It is a force of tension which is really always there between muscle and nerve and which can be awakened when electric currents are passed through them. So that in fact, that which Galvani had observed contained two things. One of them can be reproduced by purely inorganic methods, making electric currents by means of different metals with the help of liquids. The other thing which he observed is there in every organism and appears prominently in the electric fishes and certain other creatures. It is a state of tension between muscle and nerve, which, when it finds release, becomes to all appearances very like flowing electricity and its effects. It was then these discoveries which led upon the one hand to the great triumphs in materialistic science, and on the other hand provided the foundations for the immense and epoch-making technical developments which followed.

Now the fact is, the 19th century was chiefly filled with the idea that we must somehow find a single, abstract, unitary principle at the foundation of all the so-called “forces of Nature”. It was in this direction, as I said before that they interpreted what Julius Robert Mayer, the brilliant Heilbronn doctor had discovered. You will remember how we demonstrated it the other day. By mechanical force we turned a flywheel; this was attached to an apparatus whereby a mass of water was brought into inner mechanical activity. The water thereby became warmer, as we were able to shew. The effect produced—the development of warmth—may truly be attributed to the mechanical work that was done. All this was so developed and interpreted in course of time that they applied it to the most manifold phenomena of Nature,—nor was it difficult to do so within certain limits. One could release chemical forces and see how warmth arose in the process. Again, reversing the experiment which we have just described, warmth could be used in such a way as to evoke mechanical work,—as in the steam-engine and in a multitude of variations.

It was especially this so-called transformation of Nature's forces on which they riveted attention. They were encouraged to do this by what began in Julius Robert Mayer's work and then developed ever further. For it proves possible to calculate, down to the actual figures, how much warmth is needed to produce a given, measurable amount of work; and vice-versa, how much mechanical work is needed to produce a given, measurable amount of warmth or heat. So doing, they imagined—though to begin with surely there is no cause to think of it in this way—that the mechanical work, which we expended for example in making these vanes rotate in the water, has actually been transformed into the warmth. Again, they assumed that when warmth is applied in the steam-engine, this warmth is actually transformed into the mechanical work that emerges. The meditations of physicists during the 19th century kept taking this direction: they were always looking for the kinship between the diverse forces of Nature so-called,—trying to discover kinships which were to prove at last that some abstract, everywhere equal principle is at the bottom of them all, diverse and manifold as they appear. These tendencies were crowned to some extent when near the end of the century Heinrich Hertz, a physicist of some genius, discovered the so-called electric waves—here once again it was waves! It certainly seemed to justify the idea that the electricity that spreads through space is in some way akin to the light that spreads through space,—the latter too being already conceived at that time as a wave-movement in the ether.

That “electricity”—notably in the form of current electricity—cannot be grasped so simply with the help of primitive mechanical ideas, but makes it necessary to give our Physics a somewhat wider and more qualitative aspect,—this might already have been gathered from the existence of induction currents as they are called. Only to indicate it roughly: the flow of an electric current along a wire will cause a current to arise in a neighbouring wire, by the mere proximity of the one wire to the other. Electricity is thus able to take effect across space,—so we may somehow express it. Now Hertz made this very interesting discovery:—he found that the electrical influences or agencies do in fact spread out in space in a way quite akin to the spreading of waves, or to what could be imagined as such. He found for instance that if you generate an electric spark, much in the way we should be doing here, developing the necessary tension, you can produce the following result. Suppose we had a spark jumping across this gap. Then at some other point in space we could put two such “inductors”, as we may call them, opposite and at a suitable distance from one-another, and a spark would jump across here too.

This, after all, is a phenomenon not unlike what you would have if here for instance—Figure IXb—were a source of light and here a mirror. A cylinder of light is reflected, this is then gathered up again by a second mirror, and an image arises here. We may then say, the light spreads out in space and takes effect at a distance. In like manner. Hertz could now say that electricity spreads out and the effect of it is perceptible at a distance. Thus in his own conception and that of other scientists he had achieved pretty fair proof that with electricity something like a wave-movement is spreading out through space,—analogous to the way one generally imagines wave-movements to spread out. Even as light spreads out through space and takes effect at a distance, unfolding as it were, becoming manifest where it encounters other bodies, so too can the electric waves spread out, becoming manifest—taking effect once more—at a distance. You know how wireless telegraphy is based on this.

The favourite idea of 19th century physicists was once again fulfilled to some extent. For sound and light, they were imagining wave-trains, sequences of waves. Also for warmth as it spreads outward into space, they had begun to imagine wave-movements, since the phenomena of warmth are in fact similar in some respects. Now they could think the same of electricity; the waves had only to be imagined long by comparison. It seemed like incontrovertible proof that the way of thinking of 19th century Physics had been right.

Nevertheless, Hertz's experiments proved to be more like a closing chapter of the old. What happens in any sphere of life, can only properly be judged within that sphere. We have been undergoing social revolutions. They seem like great and shattering events in social life since we are looking rather intently in their direction. Look then at what has happened in Physics during the 1890's and the first fifteen years, say, of our century; you must admit that a revolution has here been going on, far greater in its domain than the external revolution in the social realm. It is no more nor less than that in Physics the old concepts are undergoing complete dissolution; only the physicists are still reluctant to admit it. Hertz's discoveries were still the twilight of the old, tending as they did to establish the old wave-theories even more firmly. What afterwards ensued, and was to some extent already on the way in his time, was to be revolutionary.

I refer now to those experiments where an electric current, which you can generate of course and lead to where you want it, is conducted through a glass tube from which the air has to a certain extent been pumped out, evacuated. The electric current, therefore, is made to pass through air of very high dilution. High tension is engendered in the tubes which you here see. In effect, the terminals from which the electricity will discharge into the tube are put far apart—as far as the length of the tube will allow. There is a pointed terminal at either end, one where the positive electricity will discharge (i.e. the positive pole) at the one end, so too the negative at the other. Between these points the electricity discharges; the coloured line which you are seeing is the path taken by the electricity. Thus we may say: What otherwise goes through the wires, appears in the form in which you see it here when it goes through the highly attenuated air. It becomes even more intense when the vacuum is higher. Look how a kind of movement is taking place from the one side and the other,—how the phenomenon gets modified. The electricity which otherwise flows through the wire: along a portion of its path we have been able, as it were, so to treat it that in its interplay with other factors it does at last reveal, to some extent, its inner essence. It shews itself, such as it is; it can no longer hide in the wire! Observe the green light on the glass; that is fluorescent light. I am sorry I cannot go into these phenomena in greater detail, but I should not get where I want to in this course if I did not go through them thus quickly. You see what is there going through the tube,—you see it in a highly dispersed condition in the highly attenuated air inside the tube.

Now the phenomena which thus appeared in tubes containing highly attenuated air or gas, called for more detailed study, in which many scientists engaged,—and among these was Crookes. Further experiments had to be made on the phenomena in these evacuated tubes, to get to know their conditions and reactions. Certain experiments, due among others to Crookes, bore witness to a very interesting fact. Now that they had at last exposed it—if I may so express myself—the inner character of electricity, which here revealed itself, proved to be very different from what they thought of light for instance being propagated in the form of wave-movements through the ether. What here revealed itself was clearly not propagated in that way. Whatever it is that is shooting through these tubes is in fact endowed with remarkable properties, strangely reminiscent of the properties of downright matter. Suppose you have a magnet or electromagnet. (I must again presume your knowledge of these things; I cannot go into them all from the beginning.) You can attract material objects with the magnet. Now the body of light that is going through this tube—this modified form, therefore, of electricity—has the same property. It too can be attracted by the electromagnet. Thus it behaves, in relation to a magnet, just as matter would behave. The magnetic field will modify what is here shooting through the tube.

Experiments of this kind led Crookes and others to the idea that what is there in the tube is not to be described as a wave-movement, propagated after the manner of the old wave-theories. Instead, they now imagined material particles to be shooting through the space inside the tube; these, as material particles, are then attracted by the magnetic force. Crookes therefore called that which is shot across there from pole to pole, (or howsoever we may describe it; something is there, demanding our consideration),—Crookes called it “radiant matter”. As a result of the extreme attenuation, he imagined, the matter that is left inside the tube has reached a state no longer merely gaseous but beyond the gaseous condition. He thinks of it as radiant matter—matter, the several particles of which are raying through space like the minutest specks of dust or spray, the single particles of which, when charged electrically, will shoot through space in this way. These particles themselves are then attracted by the electromagnetic force. Such was his line of thought: the very fact that they can thus be attracted shews that we have before us a last attenuated remnant of real matter, not a mere movement like the old-fashioned ether-movements.

It was the radiations (or what appeared as such) from the negative electric pole, known as the cathode, which lent themselves especially to these experiments. They called them “cathode rays”. Herewith the first breach had, so to speak, been made in the old physical conceptions. The process in these Hittorf tubes (Hittorf had been the first to make them, then came Geissler) was evidently due to something of a material kind—though in a very finely-divided condition—shooting through space. Not that they thereby knew what it was; in any case they did not pretend to know what so-called “matter” is. But the phenomena indicated that this was something somehow identifiable with matter,—of a material nature.

Crookes therefore was convinced that this was a kind of material spray, showering through space. The old wave-theory was shaken. However, fresh experiments now came to light, which in their turn seemed inconsistent with Crookes's theory. Lenard in 1893 succeeded in diverting the so-called rays that issue from this pole and carrying them outward. He inserted a thin wall of aluminium and led the rays out through this. The question arose: can material particles go through a material wall without more ado? So then the question had to be raised all over again:

Is it really material particles showering through space,—or is it something quite different after all? In course of time the physicists began to realize that it was neither the one nor the other: neither of the old conceptions—that of ether-waves, or that of matter—would suffice us here. The Hittorf tubes were enabling them, as it were, to pursue the electricity itself along its hidden paths. They had naturally hoped to find waves, but they found none. So they consoled themselves with the idea that it was matter shooting through space. This too now proved untenable.

At last they came to the conclusion which was in fact emerging from many and varied experiments, only a few characteristic examples of which I have been able to pick out. In effect, they said: It isn't waves, nor is it simply a fine spray of matter. It is flowing electricity itself; electricity as such is on the move. Electricity itself is flowing along here, but in its movement and in relation to other things—say, to a magnet—it shews some properties like those of matter. Shoot a material cannonball through the air and let it pass a magnet,—it will naturally be diverted So too is electricity. This is in favour of its being of a material nature. On the other hand, in going through a plate of aluminium without more ado, it shews that it isn't just matter. Matter would surely make a hole in going through other matter. So then they said: This is a stream of electricity as such. And now this flowing electricity shewed very strange phenomena. A clear direction was indeed laid out for further study, but in pursuing this direction they had the strangest experiences. Presently they found that streams were also going out from the other pole,—coming to meet the cathode rays. The other pole is called the anode; from it they now obtained the rays known as “canal rays”. In such a tube, they now imagined there to be two different kinds of ray, going in opposite directions.

One of the most interesting things was discovered in the 1890's by Roentgen ... From the cathode rays he produced a modified form of rays, now known as Roentgen rays or X-rays. They have the effect of electrifying certain bodies, and also shew characteristic reactions with magnetic and electric forces. Other discoveries followed. You know the Roentgen rays have the property of going through bodies without producing a perceptible disturbance; they go through flesh and bone in different ways and have thus proved of great importance to Anatomy and Physiology.

Now a phenomenon arose, making it necessary to think still further. The cathode rays or their modifications, when they impinge on glass or other bodies, call forth a kind of fluorescence; the materials become luminous under their influence. Evidently, said the scientists, the rays must here be undergoing further modification. So they were dealing already with many different kinds of rays. Those that first issued directly from the negative pole, proved to be modifiable by a number of other factors. They now looked round for bodies that should call forth such modifications in a very high degree—bodies that should especially transform the rays into some other form, e.g. into fluorescent rays. In pursuit of these researches it was presently discovered that there are bodies—uranium salts for example—which do not have to be irradiated at all, but under certain conditions will emit rays in their turn, quite of their own accord. It is their own inherent property to emit such rays. Prominent among these bodies were the kind that contain radium, as it is called.

Very strange properties these bodies have. They ray-out certain lines of force—so to describe it—which can be dealt with in a remarkable way. Say that we have a radium-containing body here, in a little vessel made of lead; we can examine the radiation with a magnet. We then find one part of the radiation separating off, being deflected pretty strongly in this direction by the magnet, so that it takes this form (Figure IXc). Another part stays unmoved, going straight on in this direction, while yet another is deflected in the opposite direction. The radiation, then, contains three elements. They no longer had names enough for all the different kinds! They therefore called the rays that will here be deflected towards the right, ß-rays; those that go straight on, γ-rays; and those are deflected in the opposite direction, α-rays.

Bringing a magnet near to the radiating body, studying these deflections and making certain computations, from the deflection one may now deduce the velocity of the radiation. The interesting fact emerges that the ß-rays have a velocity, say about nine-tenths the velocity of light, while the velocity of the α-rays is about one-tenth the velocity of light. We have therefore these explosions of force, if we may so describe them, which can be separated-out and analyzed and then reveal very striking differences of velocity.

Now I remind you how at the outset of these lectures we endeavoured in a purely spiritual way to understand the formula, v = s/t. We said that the real thing in space is the velocity; it is velocity which justifies us in saying that a thing is real. Here now you see what is exploding as it were, forth from the radiating body, characterized above all by the varying intensity and interplay of the velocities which it contains. Think what it signifies: in the same cylinder of force which is here raying forth, there is one element that wants to move nine times as fast as the other. One shooting force, tending to remain behind, makes itself felt as against the other that tends to go nine times as quickly. Now please pay heed a little to what the anthroposophists alone, we must suppose, have hitherto the right not to regard as sheer madness! Often and often, when speaking of the greatest activities in the Universe which we can comprehend, we had to speak of differences in velocity as the most essential thing. What is it brings about the most important things that play into the life of present time? It is the different velocities with which the normal, the Luciferic and the Ahrimanic spiritual activities work into one-another. It is that differences of velocity are there in the great spiritual streams to which the web and woof of the world is subjected. The scientific pathway which has opened out in the most recent times is compelling even Physics—though, to begin with, unconsciously—to go into differences of velocity in a way very similar to the way Spiritual Science had to do for the great all-embracing agencies of Cosmic Evolution.

Now we have not yet exhausted all that rays forth from this radium-body. The effects shew that there is also a raying-forth of the material itself. But the material thus emanated proves to be radium no longer. It presently reveals itself to be helium for instance—an altogether different substance. Thus we no longer have the conservation,—we have the metamorphosis of matter.

The phenomena to which I have been introducing you, all of them take their course in what may be described as the electrical domain. Moreover, all of them have one property in common. Their relation to ourselves is fundamentally different from that of the phenomena of sound or light for example, or even the phenomena of warmth. In light and sound and warmth we ourselves are swimming, so to speak, as was described in former lectures. The same cannot be said so simply of our relation to the electrical phenomena. We do not perceive electricity as a specific quality in the way we perceive light, for instance. Even when electricity is at last obliged to reveal itself, we perceive it by means of a phenomenon of light. This led to people's saying, what they have kept repeating: “There is no sense-organ for electricity in man.” The light has built for itself in man the eye—a sense-organ with which to see it. So has the sound, the ear. For warmth too, a kind of warmth-organ is built into man. For electricity, they say, there is nothing analogous. We perceive electricity indirectly.

We do, no doubt; but that is all that can be said of it till you go forward to the more penetrating form of Science which we are here at least inaugurating. In effect, when we expose ourselves to light, we swim in the element of light in such a way that we ourselves partake in it with our conscious life, or at least partially so. So do we in the case of warmth and in that of sound or tone. The same cannot be said of electricity. But now I ask you to remember what I have very often explained: as human beings we are in fact dual beings. That is however to put it crudely, for we are really threefold beings: beings of Thought, of Feeling and of Will. Moreover, as I have shewn again and again, it is only in our Thinking that we are really awake, whilst in our feelings we are dreaming and in our processes of will we are asleep—asleep even in the midst of waking life. We do not experience our processes of will directly. Where the essential Will is living, we are fast asleep. And now remember too, what has been pointed out during these lectures. Wherever in the formulae of Physics we write m for mass, we are in fact going beyond mere arithmetic—mere movement, space and time. We are including what is no longer purely geometrical or kinematical, and as I pointed out, this also corresponds to the transition of our consciousness into the state of sleep. We must be fully clear that this is so. Consider then this memberment of the human being; consider it with fully open mind, and you will then admit: Our experience of light, sound and warmth belongs—to a high degree at least, if not entirely—to the field which we comprise and comprehend with our sensory and thinking life. Above all is this true of the phenomena of light. An open-minded study of the human being shews that all these things are akin to our conscious faculties of soul. On the other hand, the moment we go on to the essential qualities of mass and matter, we are approaching what is akin to those forces which develop in us when we are sleeping. And we are going in precisely the same direction when we descend from the realm of light and sound and warmth into the realm of the electrical phenomena.

We have no direct experience of the phenomena of our own Will; all we are able to experience in consciousness is our thoughts about them. Likewise we have no direct experience of the electrical phenomena of Nature. We only experience what they deliver, what they send upward, to speak, into the realms of light and sound and warmth etc. For we are here crossing the same boundary as to the outer world, which we are crossing in ourselves when we descend from our thinking and idea-forming, conscious life into our life of Will. All that is light, and sound, and warmth, is then akin to our conscious life, while all that goes on in the realms of electricity and magnetism is akin—intimately akin—to our unconscious life of Will. Moreover the occurrence of physiological electricity in certain lower animals is but the symptom—becoming manifest somewhere in Nature—of a quite universal phenomenon which remains elsewhere unnoticed. Namely, wherever Will is working through the metabolism, there is working something very similar to the external phenomena of electricity and magnetism.

When in the many complicated ways—which we have only gone through in the barest outline in today's lecture—when in these complicated ways we go down into the realm of electrical phenomena, we are in fact descending into the very same realm into which we must descend whenever we come up against the simple element of mass. What are we doing then when we study electricity and magnetism? We are then studying matter, in all reality. It is into matter itself that you are descending when you study electricity and magnetism. And what an English philosopher has recently been saying is quite true—very true indeed. Formerly, he says, we tried to imagine in all kinds of ways, how electricity is based on matter. Now on the contrary we must assume, what we believe to be matter, to be in fact no more than flowing electricity. We used to think of matter as composed of atoms; now we must think of the electrons, moving through space and having properties like those we formerly attributed to matter.

In fact our scientists have taken the first step—they only do not yet admit it—towards the overcoming of matter. Moreover they have taken the first step towards the recognition of the fact that when in Nature we pass on from the phenomena of light, sound and warmth of those of electricity, we are descending—in the realm of Nature—into phenomena which are related to the former ones as is the Will in us to the life of Thought. This is the gist and conclusion of our studies for today, which I would fain impress upon your minds. After all, my main purpose in these lectures is to tell you what you will not find in the text-books. The text-book knowledge I may none the less bring forward, is only given as a foundation for the other.

My dear Friends,

I will now bring these few improvised hours of scientific study to a provisional conclusion. I want to give you a few guiding lines which may help you in developing such thoughts about Nature for yourselves, taking your start from characteristic facts which you can always make visible by experiment. In Science today—and this applies above all to the teacher—it is most important to develop a right way of thinking upon the facts and phenomena presented to us by Nature. You will remember what I was trying to shew yesterday in this connection. I shewed how since the 1890's physical science has so developed that materialism is being lifted right out of its bearings, so to speak, even by Physics itself. This is the point to remember above all in this connection.

The period when Science thought that it had golden proofs of the universality of waves and undulations was followed, as we say, by a new time. It was no longer possible to hold fast to the old wave-theories. The last three decades have in fact been revolutionary. One can imagine nothing more revolutionary in any realm than this most recent period has been in Physics. Impelled by the very facts that have not emerged, Physics has suffered no less a loss than the concept of matter itself in its old form. Out of the old ways of thinking, as we have seen, the phenomena of light had been brought into a very near relation to those of electricity and magnetism. Now the phenomena produced by the passage of electricity through tubes in which the air or gas was highly rarefied, led scientists to see in the raying light itself something like radiating electricity. I do not say that they were right, but this idea arose. It came about in this way:—The electric current until then had always been hidden as it were in wires, and one had little more to go on than Ohm's Law. Now one was able, so to speak, to get a glimpse of the electricity itself, for here it leaves the wire, jumps to the distant pole, and is no longer able as it were to conceal its content in the matter through which it passes.

The phenomena proved complicated. As we say yesterday, manifold types of radiation emerged. The first to be discovered were the so-called cathode rays, issuing from the negative pole of the Hittorf tube and making their way through the partial vacuum. In that they can be deflected by magnetic forces, they prove akin to what we should ordinarily feel to be material. Yet they are also evidently akin to what we see where radiations are at work. This kinship comes out most vividly when we catch the rays (or whatsoever it is that is issuing from the negative electric pole) upon a screen or other object, as we should do with light. Light throws a shadow. So do these radiations. Yet in this very experiment we are again establishing the near relation of these rays to the ordinary element of matter. For you can imagine that a bombardment is taking place from here (as we say yesterday, this is how Crookes thinks of the cathode rays). The “bombs” do not get through the screen which you put in the way; the space behind the screen is protected. This can be shewn by Crookes's experiment, interposing a screen in the way of the cathode rays.

We will here generate the electric current; we pass it through this tube in which the air is rarefied. It has its cathode or negative pole here, its anode or positive pole here. Sending the electricity through the tube, we are now getting the so-called cathode rays. We catch them on a screen shaped like a St. Andrew's cross. We let the cathode rays impinge on it, and on the other side you will see something like a shadow of the St. Andrew's cross, from which you may gather that the cross stops the rays. Observe it clearly, please. Inside the tube is the St. Andrew's cross. The cathode rays go along here; here they are stopped by the cross; the shadow of the cross becomes visible upon the wall of the vessel behind it. I will now bring the shadow which is thus made visible into the field of a magnet. I beg you to observe it now. You will find the shadow influenced by the magnetic field. You see then, just as I might attract a simple bit of iron with a magnet, so too, what here emerges like a kind of shadow behaves like external matter. It behaves materially.

Here then we have a type of rays which Crookes regards as “radiant matter”—as a form of matter neither solid, liquid or gaseous but even more attenuated,—revealing also that electricity itself, the current of electricity, behaves like simple matter. We have, as it were, been trying to look at the current of flowing electricity as such, and what we see seems very like the kind of effects we are accustomed to see in matter.

I will now shew you, what was not possible yesterday, the rays that issue from the other pole and that are called “canal rays”. You can distinguish the rays from the cathode, going in this direction, shimmering in a violet shade of colour, and the canal rays coming to meet them, giving a greenish light. The velocity of the canal rays is much smaller.

Finally I will shew you the kind of rays produced by this apparatus: they are revealed in that the glass becomes fluorescent when we send the current through. This is the kind of rays usually made visible by letting them fall upon a screen of barium platinocyanide. They have the property of making the glass intensely fluorescent. Please observe the glass. You see it shining with a very strong, greenish-yellow, fluorescent light. The rays that shew themselves in this way are the Roentgen rays or X-rays, mentioned yesterday. We observe this kind too, therefore.

Now I was telling you how in the further study of these things it appeared that certain entities, regarded as material substances, emit sheaves of rays—rays of three kinds, to begin with. We distinguished them as \(\alpha\)-, \(\beta\)-, and \(\gamma\)-rays (cf. the Figure IXc). They shew distinct properties. Moreover, yet another thing emerges from these materials, known as radium etc. It is the chemical element itself which as it were gives itself up completely. In sending out its radiation, it is transmuted. It changes into helium, for example; so it becomes something quite different from what it was before. We have to do no longer with stable and enduring matter but with a complete metamorphosis of phenomena.

Taking my start from these facts, I now want to unfold a point of view which may become for you an essential way, not only into these phenomena but into those of Nature generally. The Physics of the 19th century chiefly suffered from the fact that the inner activity, with which man sought to follow up the phenomena of Nature, was not sufficiently mobile in the human being himself. Above all, it was not able really to enter the facts of the outer world. In the realm of light, colours could be seen arising, but man had not enough inner activity to receive the world of colour into his forming of ideas, into his very thinking. Unable any longer to think the colours, scientists replaced the colours, which they could not think, by what they could,—namely by what was purely geometrical and kinematical—calculable waves in an unknown ether. This “ether” however, as you must see, proved a tricky fellow. Whenever you are on the point of catching it, it evades you. It will not answer the roll-call. In these experiments for instance, revealing all these different kinds of rays, the flowing electricity has become manifest to some extent, as a form of phenomenon in the outer world,—but the “ether” refuses to turn up. In fact it was not given to the 19th-century thinking to penetrate into the phenomena. But this is just what Physics will require from now on. We have to enter the phenomena themselves with human thinking. Now to this end certain ways will have to be opened up—most of all for the realm of Physics.

You see, the objective powers of the World, if I may put it so,—those that come to the human being rather than from him—have been obliging human thought to become rather more mobile (albeit, in a certain sense, from the wrong angle). What men regarded as most certain and secure, that they could most rely on, was that they could explain the phenomena so beautifully by means of arithmetic and geometry—by the arrangement of lines, surfaces and bodily forms in space. But the phenomena in these Hittorf tubes are compelling us to go more into the facts. Mere calculations begin to fail us here, if we still try to apply them in the same abstract way as in the old wave-theory.

Let me say something of the direction from which it first began, that we were somehow compelled to bring more movement into our geometrical and arithmetical thinking. Geometry, you know, was a very ancient science. The regularities and laws in line and triangle and quadrilateral etc.,—the way of thinking all these forms in pure Geometry—was a thing handed down from ancient time. This way of thinking was now applied to the external phenomena presented by Nature. Meanwhile however, for the thinkers of the 19th century, the Geometry itself began to grow uncertain. It happened in this way. Put yourselves back into your school days: you will remember how you were taught (and our good friends, the Waldorf teachers, will teach it too, needless to say; they cannot but do so),—you were undoubtedly taught that the three angles of a triangle (Figure Xa) together make a straight angle—an angle of 180°. Of course you know this. Now then we have to give our pupils some kind of proof, some demonstration of the fact. We do it by drawing a parallel to the base of the triangle through the vertex. We then say: the angle \(\alpha\), which we have here, shews itself here again as \(\alpha'\). \(\alpha\) and \(\alpha'\) are alternate angles and therefore equal. I can transfer this angle over here, then. Likewise this angle \(\beta\), over here; again it remains the same.

The angle \(\gamma\) stays where it is. If then I have \(\gamma = \gamma'\), \(\alpha = \alpha'\) and \(\beta=\beta'\), while \(\alpha'+\beta;' + \gamma'\) taken together give an angle of 180° as they obviously do, \(\alpha + \beta + \gamma\) will do the same. Thus I can prove it so that you actually see it. A clearer or more graphic proof can scarcely be imagined.

However, what we are taking for granted is that this upper line A'B' is truly parallel to the lower line \(AB\),—for this alone enables me to carry out the proof. Now in the whole of Euclid's Geometry there is no way of proving that two lines are really parallel, i.e. that they only meet at an infinite distance, or do not meet at all. They only look parallel so long as I hold fast to a space that is merely conceived in thought. I have no guarantee that it is so in any real space. I need only assume that the two lines meet, in reality, short of an infinite distance; then my whole proof, that the three angles together make 180°, breaks down. For I should then discover: whilst in the space which I myself construct in thought—the space of ordinary Geometry—the three angles of a triangle add up to 180° exactly, it is no longer so when I envisage another and perhaps more real space. The sum of the angles will no longer be 180°, but may be larger. That is to say, besides the ordinary geometry handed down to us from Euclid other geometries are possible, for which the sum of the three angles of a triangle is by no means 180°.

Nineteenth century thinking went a long way in this direction, especially since Lobachevsky, and from this starting-point the question could not but arise: Are then the processes of the real world—the world we see and examine with our senses—ever to be taken hold of in a fully valid way with geometrical ideas derived from a space of our own conceiving? We must admit: the space which we conceive in thought is only thought. Nice as it is to cherish the idea that what takes place outside us partly accords with what we figure-out about it, there is no guarantee that it really is so. There is no guarantee that what is going on in the outer world does really work in such a way that we can fully grasp it with the Euclidean Geometry which we ourselves think out. Might it not be—the facts alone can tell—might it not be that the processes outside are governed by quite another geometry, and it is only we who by our own way of thinking first translate this into Euclidean geometry and all the formulae thereof?

In a word, if we only go by the resources of Natural Science as it is today, we have at first no means whatever of deciding, how our own geometrical or kinematical ideas are related to what appears to us in outer Nature. We calculate Nature's phenomena in the realm of Physics—we calculate and draw them in geometrical figures. Yet, are we only drawing on the surface after all, or are we penetrating to what is real in Nature when we do so? What is there to tell? If people once begin to reflect deeply enough in modern Science—above all in Physics—they will then see that they are getting no further. They will only emerge from the blind alley if they first take the trouble to find out what is the origin of all our phoronomical—arithmetical, geometrical and kinematical—ideas. What is the origin of these, up to and including our ideas of movement purely as movement, but not including the forces? Whence do we get these ideas? We may commonly believe that we get them on the same basis as the ideas we gain when we go into the outer facts of Nature and work upon them with our reason. We see with our eyes and hear with our ears. All that our senses thus perceive,—we work upon it with our intellect in a more primitive way to begin with, without calculating, or drawing it geometrically, or analyzing the forms of movement. We have quite other categories of thought to go on when our intellect is thus at work on the phenomena seen by the senses. But if we now go further and begin applying to what goes on in the outer world the ideas of “scientific” arithmetic and algebra, geometry and kinematics, then we are doing far more—and something radically different. For we have certainly not gained these ideas from the outer world. We are applying ideas which we have spun out of our own inner life. Where then do these ideas come from? That is the cardinal question. Where do they come from? The truth is, these ideas come not from our intelligence—not from the intelligence which we apply when working up the ideas derived from sense-perception. They come in fact from the intelligent part of our Will. We make them with our Will-system—with the volitional part of our soul.

The difference is indeed immense between all the other ideas in which we live as intelligent beings and on the other hand the geometrical, arithmetical and kinematical ideas. The former we derive from our experience with the outer world; these on the other hand—the geometrical, the arithmetical ideas—rise up from the unconscious part of us, from the Will-part which has its outer organ in the metabolism. Our geometrical ideas above all spring from this realm; they come from the unconscious in the human being. And if you now apply these geometrical ideas (I will say “geometrical” henceforth to represent the arithmetical and algebraic too) to the phenomena of light or sound, then in your process of knowledge you are connecting, what arises from within you, with what you are perceiving from without. In doing so you remain utterly unconscious of the origin of the geometry you use. You unite it with the external phenomena, but you are quite unconscious of its source. So doing, you develop theories such as the wave-theory of light, or Newton's corpuscular theory,—it matters not which one it is. You develop theories by uniting what springs from the unconscious part of your being with what presents itself to you in conscious day-waking life. Yet the two things do not directly belong to one-another. They belong as little, my dear Friends, as the idea-forming faculty which you unfold when half-asleep belongs directly to the outer things which in your dreaming, half-asleep condition you perceive. In anthroposophical lectures I have often given instances of how the dream is wont to symbolize. An undergraduate dreams that at the door of the lecture-theatre he gets involved in a quarrel. The quarrel grows in violence; at last they challenge one-another to a duel. He goes on dreaming: the duel is arranged, they go out into the forest, he sees himself firing the shot,—and at the moment he wakes up. A chair has fallen over. This was the impact which projected itself forward into the dream. The idea-forming faculty has indeed somehow linked up with the outer phenomenon, but in a merely symbolizing way,—in no way consistent with the real object. So too, what in your geometrical and phoronomical thinking you fetch up from the subconscious part of your being, when you connect it with the phenomena of light. What you then do has no other value for reality than what finds expression in the dream when symbolizing an objective fact such as the fall and impact of the chair. All this elaboration of the outer world—optical, acoustic and even thermal to some extent (the phenomena of warmth)—by means of geometrical, arithmetical and kinematical thought-forms, is in point of fact a dreaming about Nature. Cool and sober as it may seem, it is a dream—a dreaming while awake. Moreover, until we recognize it for what it is, we shall not know where we are in our Natural Science, so that our Science gives us reality. What people fondly believe to be the most exact of Sciences, is modern mankind's dream of Nature.

But it is different when we go down from the phenomena of light and sound, via the phenomena of warmth, into the realm we are coming into with these rays and radiations, belonging as they do to the science of electricity. For we then come into connection with what in outer Nature is truly equivalent to the Will in Man. The realm of Will in Man is equivalent to this whole realm of action of the cathode rays, canal rays, Roentgen rays. \(\alpha\)-, \(\beta\)- and \(\gamma\)-rays and so on. It is from this very realm—which, once again, is in the human being the realm of Will,—it is from this that there arises what we possess in our mathematics, in our geometry, in our ideas of movement. These therefore are the realms, in Nature and in Man, which we may truly think of as akin to one-another. However, human thinking has in our time not yet gone far enough, really to think its way into these realms. Man of today can dream quite nicely, thinking out wave-theories and the like, but he is not yet able to enter with real mathematical perception into that realm of phenomena which is akin to the realm of human Will, in which geometry and arithmetic originate. For this, our arithmetical, algebraical and geometrical thinking must in themselves become more saturated with reality. It is along these lines that physical science should now seek to go.

Nowadays, if you converse with physicists who were brought up in the golden age of the old wave-theory, you will find many of them feeling a little uncanny about these new phenomena, in regard to which ordinary methods of calculation seem to break down in so many places. In recent times the physicists have had recourse to a new device. Plain-sailing arithmetical and geometrical methods proving inadequate, they now introduce a kind of statistical method. Taking their start more from the outer empirical data, they have developed numerical relations also empirical in kind. They then use the calculus of probabilities. Along these lines it is permissible to say: By all means let us calculate some law of Nature; it will hold good throughout a certain series, but then there comes a point where it no longer works.

There are indeed many things like this in modern Physics,—very significant moments where they lose hold of the thought, yet in the very act of losing it get more into reality. Conceivably for instance, starting from certain rigid ideas about the nature of a gas or air under the influence of warmth and in relation to its surroundings, a scientist of the past might have proved with mathematical certainty that air could not be liquefied. Yet air was liquefied, for at a certain point it emerged that the ideas which did indeed embrace the prevailing laws of a whole series of facts, ceased to hold good at the end of this series. Many examples might be cited. Reality today—especially in Physics—often compels the human being to admit this to himself: “You with your thinking, with your forming of ideas, no longer fully penetrate into reality; you must begin again from another angle.”

We must indeed; and to do this, my dear Friends, we must become aware of the kinship between all that comes from the human Will—whence come geometry and kinematics—and on the other hand what meets us outwardly in this domain that is somehow separated from us and only makes its presence known to us in the phenomena of the other pole. For in effect, all that goes on in these vacuum tubes makes itself known to us in phenomena of light, etc. Whatever is the electricity itself, flowing through there, is imperceptible in the last resort. Hence people say: If only we had a sixth sense—a sense for electricity—we should perceive it too, directly. That is of course wide of the mark. For it is only when you rise to Intuition, which has its ground in the Will, it is only then that you come into that region—even of the outer world—where electricity lives and moves. Moreover when you do so you perceive that in these latter phenomena you are in a way confronted by the very opposite than in the phenomena of sound or tone for instance. In sound or in musical tone, the very way man is placed into this world of sound and tone—as I explained in a former lecture—means that he enters into the sound or tone with his soul and only with his soul. What he then enters into with his body, is no more than what sucks-in the real essence of the sound or tone. I explained this some days ago; you will recall the analogy of the bell-jar from which the air has been pumped out. In sound or tone I am within what is most spiritual, while what the physicist observes (who of course cannot observe the spiritual nor the soul) is but the outer, so-called material concomitant, the movement of the wave. Not so in the phenomena of the realm we are now considering, my dear Friends. For as I enter into these, I have outside me not only the objective, so-called material element, but also what in the case of sound and tone is living in me—in the soul and spirit. The essence of the sound or tone is of course there in the outer world as well, but so am I. With these phenomena on the other hand, what in the case of sound could only be perceived in soul, is there in the same sphere in which—for sound—I should have no more than the material waves. I must now perceive physically, what in the case of sound or tone I can only perceive in the soul.

Thus in respect of the relation of man to the external world the perceptions of sound, and the perceptions of electrical phenomena for instance, are at the very opposite poles. When you perceive a sound you are dividing yourself as it were into a human duality. You swim in the elements of wave and undulation, the real existence of which can of course be demonstrated by quite external methods. Yet as you do so you become aware; herein is something far more than the mere material element. You are obliged to kindle your own inner life—your life of soul—to apprehend the tone itself. With your ordinary body—I draw it diagrammatically (the oval in Figure Xb)—you become aware of the undulations. You draw your ether—and astral body together, so that they occupy only a portion of your space. You then enjoy, what you are to experience of the sound or tone as such, in the thus inwarded and concentrated etheric-astral part of your being. It is quite different when you as human being meet the phenomena of this other domain, my dear Friends. In the first place there is no wave or undulation or anything like that for you to dive into; but you now feel impelled to expand what in the other case you concentrated (Figure Xc). In all directions, you drive your ether—and astral body out beyond your normal surface; you make them bigger, and in so doing you perceive these electrical phenomena.

Without including the soul and spirit of the human being, it will be quite impossible to gain a true or realistic conception of the phenomena of Physics. Ever-increasingly we shall be obliged to think in this way. The phenomena of sound and tone and light are akin to the conscious element of Thought and Ideation in ourselves, while those of electricity and magnetism are akin to the sub-conscious element of Will. Warmth is between the two. Even as Feeling is intermediate between Thought and Will, so is the outer warmth in Nature intermediate between light and sound on the one hand, electricity and magnetism on the other. Increasingly therefore, this must become the inner structure of our understanding of the phenomena of Nature. It can indeed become so if we follow up all that is latent in Goethe's Theory of Colour. We shall be studying the element of light and tone on the one hand, and of the very opposite of these—electricity and magnetism—on the other. As in the spiritual realm we differentiate between the Luciferic, that is akin to the quality of light, and the Ahrimanic, akin to electricity and magnetism, so also must we understand the structure of the phenomena of Nature. Between the two lies what we meet with in the phenomena of Warmth.

I have thus indicated a kind of pathway for this scientific realm,—a guiding line with which I wished provisionally to sum up the little that could be given in these few improvised hours. It had to be arranged so quickly that we have scarcely got beyond the good intentions we set before us. All I could give were a few hints and indications; I hope we shall soon be able to pursue them further. Yet, little as it is, I think what has been given may be of help to you—and notably to the Waldorf School teachers among you when imparting scientific notions to the children. You will of course not go about it in a fanatical way, for in such matters it is most essential to give the realities a chance to unfold. We must not get our children into difficulties. But this at least we can do: we can refrain from bringing into our teaching too many untenable ideas—ideas derived from the belief that the dream-picture which has been made of Nature represents actual reality. If you yourselves are imbued with the kind of scientific spirit with which these lectures—if we may take them as a fair example—have been pervaded, it will assuredly be of service to you in the whole way you speak with the children about natural phenomena.

Methodically too, you may derive some benefit. I am sorry it was necessary to go through the phenomena at such breakneck speed. Yet even so, you will have seen that there is a way of uniting what we see outwardly in our experiments with a true method of evoking thoughts and ideas, so that the human being does not merely stare at the phenomena but really thinks about them. If you arrange your lessons so as to get the children to think in connection with the experiments—discussing the experiments with them intelligently—you will develop a method, notably in the Science lessons, whereby these lessons will be very fruitful for the children who are entrusted to you.

Thus by the practical example of this course, I think I may have contributed to what was said in the educational lectures at the inception of the Waldorf School. I believe therefore that in arranging these scientific courses we shall also have done something for the good progress of our Waldorf School, which ought really to prosper after the good and very praiseworthy start which it has made. The School was meant as a beginning in a real work for the evolution of our humanity—a work that has its fount in new resources of the Spirit. This is the feeling we must have. So much is crumbling, of all that has developed hitherto in human evolution. Other and new developments must come in place of what is breaking down. This realization in our hearts and minds will give the consciousness we need for the Waldorf School. In Physics especially it becomes evident, how many of the prevailing ideas are in decay. More than one thinks, this is connected with the whole misery of our time. When people think sociologically, you quickly see where their thinking goes astray. Admittedly, here too most people fail to see it, but you can at least take notice of it; you know that sociological ways of thought will find their way into the social order of mankind. On the other hand, people fail to realize how deeply the ideas of Physics penetrate into the life of mankind. They do not know what havoc has in fact been wrought by the conceptions of modern Physics, terrible as these conceptions often are. In public lectures I have often quoted Hermann Grimm. Admittedly, he saw the scientific ideas of his time rather as one who looked upon them from outside. Yet he spoke not untruly when he said, future generations would find it difficult to understand that there was once a world so crazy as to explain the evolution of the Earth and Solar System by the theory of Kant and Laplace. To understand such scientific madness would not be easy for a future age, thought Hermann Grimm. Yet in our modern conceptions of inorganic Nature there are many features like the theory of Kant and Laplace. And you must realize how much is yet to do for the human beings of our time to get free of the ways of Kant and Konigsberg and all their kindred. How much will be to do in this respect, before they can advance to healthy, penetrating ways of thought!

Strange things one witnesses indeed from time to time, shewing how what is wrong on one side joins up with what is wrong on another. What of a thing like this? Some days ago—as one would say, by chance—I was presented with a reprint of a lecture by a German University professor. (He prides himself in this very lecture that there is in him something of Kant and Konigsberg!) It was a lecture in a Baltic University, on the relation of Physics and Technics, held on the 1st of May 1918,—please mark the date! This learned physicist of our time in peroration voices his ideal, saying in effect: The War has clearly shewn that we have not yet made the bond between Militarism and the scientific laboratory work of our Universities nearly close enough. For human progress to go on in the proper way, a far closer link must in future be forged between the military authorities and what is being done at our Universities. Questions of mobilization in future must include all that Science can contribute, to make the mobilization still more effective. At the beginning of the War we suffered greatly because the link was not yet close enough—the link which we must have in future, leading directly from the scientific places of research into the General Staffs of our armies.

Mankind, my dear Friends, must learn anew, and that in many fields. Once human beings make up their minds to learn anew in such a realm as Physics, they will be better prepared to learn anew in other fields as well. Those physicists who go on thinking in the old way, will never be so very far removed from the delightful coalition between the scientific laboratories and the General Staffs. How many things will have to alter! So may the Waldorf School be and remain a place where the new things which mankind needs can spring to life. In the expression of this hope, I will conclude our studies for the moment.

Rudolf Steiner, in all that he created and gave to the world, took his start from real needs,—never from theoretical programmes. Time and again, what he gave took its inception from the spiritual questions and interests of individuals or groups among his friends and pupils. Yet as the faculty to apprehend the spiritual aspect of the World first had to be rekindled and awakened in our time—a slow and gradual process—it must have signified a very great sacrifice and a severe hindrance for this universal spirit to bring the spiritual truths from infinite horizons into the narrower range of outlook of his contemporaries. This sacrifice he did not shun. Even into the anxiously constraining walls of earth 20th-century scientific thinking he brought the light of spiritual knowledge, and we who have received this cannot find adequate words in which to thank him. Our truest thanks must be the will to widen out our own horizon, thus making easier the teacher's task.

The Anthroposophical Movement within this 20th century is seeking to bring about a return from materialism to a spiritual understanding of the World. It is a good thing for mankind that in this Movement some individualities have also chosen the very hardest task, namely to lead again to spiritual sources that realm of human knowledge which has plunged most deeply into agnostic materialism—Natural Science. Future generations will surely be very grateful to the scientists—teachers of the Waldorf School at Stuttgart above all—who had the inner courage to put their questions to the great spiritual teacher.

We take this opportunity to thank those who have hitherto administered this spiritual treasure—who first revised and duplicated the notes of the lectures, thereby preserving them for posterity. We refer especially to the Waldorf School teachers E. A. K. Stockmeyer, Alexander Strakosch, and above all Dr. Eugen Kolisko and Dr. Walter Johannes Stein. My thanks are also due to Ehrenfried Pfeiffer of Dornach for his assistance in preparing the present edition.¹

It will be well for us to refer at this point to the following passages from Rudolf Steiner's Autobiography:—

“The anthroposophical period of my life-work began at a time when many people were feeling dissatisfied with the ways of knowledge of the immediate past. They looked for ways to get beyond that realm of existence to which the scientific era was restricted inasmuch as nothing was held valid as “secure knowledge” unless it could be grasped in mechanistic forms of thought. The strivings of many of our contemporaries towards some form of spiritual knowledge touched me deeply. There were biologists for instance such as Oskar Hertwig. Having begun his career as a disciple of Haeckel, he afterwards took leave of Darwinism, for he now felt that the driving forces recognized by the Darwinian school were inadequate to explain the facts of organic evolution. The longing of our time for knowledge seemed to me to find expression in such men as these. And yet it seemed to me this longing was oppressed by a heavy load—a burden due to the belief that only those things which we can investigate by means of the outer senses and then express in terms of measure, number and weight, constitute genuine knowledge. Men did not venture to unfold that inner activity of thought by means of which reality is experienced more intimately than by the physical senses. The most they did was to declare that with the kind of scientific explanation hitherto applied also to higher forms of reality—those of organic life for example—no fundamental progress was possible. If a more positive contribution was looked for,—if they were now to say what it is that works in the realm of life—they could bring forward only the vaguest notions.

“Those who were striving to transcend the mechanical explanation of the World generally lacked the courage to admit that if we want to overcome the mechanistic system we must also overcome the habits of thought which have led to it. The time was calling, yet called in vain, for a clear recognition of this kind. The orientation of our faculties of knowledge towards the outer senses enables us to penetrate what is mechanical in Nature. This mental tendency has become habitual throughout the second half of the 19th century. If the mechanical aspect of the world no longer satisfied us now, we ought not to expect to reach into higher regions in the identical frame of mind. The outer senses develop and awaken in the human being, so to speak, of their own accord; but on this basis we can only gain insight into the mechanical domain. If we desire to know more than this, we must by dint of our own efforts give to our deeper, latent faculties of knowledge the same development which Nature gives the powers of the senses. The faculties with which we apprehend what is mechanical are awake of their own accord; those that apply to higher realms of reality first need to be awakened.

“The time required, so it seemed to me, that in our striving after knowledge we should arrive at this clear recognition of our state, and I was happy when I saw any beginnings or indications that seemed to tend in this direction. . . .”

“There now exists a twofold outcome of the anthroposophical period of my life-work. There are my published books upon the one hand, while on the other hand there are a larger number of lecture-courses, printed at first for private circulation and available, to begin with, only to members of the Anthroposophical Society. These printed versions of my lectures are reports, more or less accurately made, which I was quite unable to correct for want of time. It would have pleased me best to let the spoken word remain as spoken word; but members wanted the lectures made available in printed form; so it was done. . . .

“To gain a picture of my own inner work, my unceasing effort to present the spiritual science of Anthroposophia to the prevailing consciousness of our time, one must have recourse to my published writings. In these I tried to come to terms with the modern striving after knowledge in its many aspects. Here I set forth, what in the realm of spiritual perception grew for me ever more fully and clearly into the edifice of “Anthroposophia”, admittedly imperfect as it still is in many ways. Herein I saw my essential task, in the fulfilment of which I only had to bear in mind what is required when communications from the spiritual world are imparted to the prevailing culture of our time. Yet side by side with this requirement I had to do full justice to another one, namely to meet the inner needs and spiritual longings that became manifest among the members of the Society.

“To this end the many lecture-courses were given in the Society; and this involved another circumstance. The lectures were attended by members only. Acquainted as they were already with the initial teachings of Anthroposophia, one could speak to them as to more advanced students. Thus the whole tenor of these member's lectures came to be different from what was possible in written books intended for the world at large. In these more intimate circles I might speak of many things in a form which I should certainly have had to change had I intended it for publication from the outset.

“Competent judgment on the content of these privately printed lectures will of course only be possible for those who are acquainted with the premisses of thought, taken for granted in those who heard them. For the great majority of these reprints, this implies at the very least some knowledge of the anthroposophical science of Man and of the essence of the great Universe as described in Anthroposophia; also a knowledge of ‘anthroposophical History’, for this too is an essential part of the communications from the spiritual world.”

Whoever reads the lectures here reproduced should bear the foregoing words in mind. If those who work with this lecture-course approach it with the will “to awaken in themselves the faculties of knowledge for higher forms of reality”, the time will surely come when the dead mechanistic picture of the world which the last century produced will be transcended—transcended above all by the most up-to-day, the most gifted and conscientious of our scientists, who will then see through the inherent impossibility and untruth of this world-picture. Then will the far more living and spiritual form of Science which Rudolf Steiner had in mind reveal its truth and beauty, also its ethical inspiring power. The Section calls to all its fellow-workers: Help the Goetheanum bring about the beginning of this new epoch even within the present century. For generations due to come at the end of the 20th century, let there be in existence a Science of Nature permeated with the living Spirit, permeated with the Christ-Impulse!

For the Natural Science Section at the Goetheanum
Guenther Wachsmuth.
Dornach, January 1925.

• 1. TRANSLATOR: The English version (1948) has been based on this edition, and on a number of corrections and improvements, issued a few years ago by Paul Eugen Schiller of Dornach.

At the beginning of this scientific lecture-course, Dr. Walter Johannes Stein read out the following quotations:—

From Goethe's Scientific Works, Kuerschner's Edition, Vol. 3 (1890), page XVII of the Introduction by Rudolf Steiner:—

“Needless to say I am not wanting to defend Goethe's Theory of Colour in every detail. It is the underlying principle which I would like to see maintained. Nor could it here be my task to derive from this principle the phenomena of colour which were not yet known in Goethe's time. I could only do justice to such a task if I were fortunate enough one day to have the leisure and the means to write a scientifically up-to-date Theory of Colour in Goethe's spirit.”

Fr. Vol. 1 of the same Edition (1883), page LXXXIV of the Introduction by Rudolf Steiner:

“May scientists and thinkers young in mind and in ideal—those above all who seek not only to extend the range of information but who look deep into the central issues of our life of knowledge—pay heed to what I have set forth and follow in large numbers, so to work out more fully and more perfectly what I have here attempted.”

From The Spiritual Guidance of Man and of Mankind by Rudolf Steiner (1911):

“In time to come there will be physicists and chemists whose teaching will not be such as now prevails under the influence of the Egypto-Chaldean Spirits that have remained behind, but who will teach that Matter is built up in the way in which the Christ has gradually ordained it. Even into the laws of Chemistry and Physics the Christ will be found. Thus will a spiritual form of Chemistry and Physics come to pass in future”.

My dear friends,

The present course of lectures will constitute a kind of continuation of the one given when I was last here. I will begin with those chapters of physics which are of especial importance for laying a satisfactory foundation for a scientific world view, namely the observations of heat relations in the world. Today I will try to lay out for you a kind of introduction to show the extent to which we can create a body of meaningful views of a physical sort within a general world view. This will show further how a foundation may be secured for a pedagogical impulse applicable to the teaching of science. Today we will therefore go as far as we can towards outlining a general introduction.

The theory of heat, so-called, has taken a form during the 19th century which has given a great deal of support to a materialistic view of the world. It has done so because in heat relationships it is very easy to turn one's glance away from the real nature of heat, from its being, and to direct it to the mechanical phenomena arising from heat.

Heat is first known through sensations of cold, warmth, lukewarm, etc. But man soon learns that there appears to be something vague about these sensations, something subjective. A simple experiment which can be made by anyone shows this fact.

Imagine you have a vessel filled with water of a definite temperature, \(t\); on the right of it you have another vessel filled with water of a temperature \(t-t_1\), that is of a temperature distinctly lower than the temperature in the first vessel. In addition, you have a vessel filled with water at a temperature \(t+t_1\). When now, you hold your fingers in the two outer vessels you will note by your sensations the heat conditions in these vessels. You can then plunge your fingers which have been in the outer vessels into the central vessel and you will see that to the finger which has been in the cold water the water in the central vessel will feel warm, while to the finger which has been in the warm water, the water in the central vessel will feel cold. The same temperature therefore is experienced differently according to the temperature to which one has previously been exposed. Everyone knows that when he goes into a cellar, it may feel different in winter from the way it feels in summer. Even though the thermometer stands at the same point circumstances may be such that the cellar feels warm in the winter and cool in the summer. Indeed, the subjective experience of heat is not uniform and it is necessary to set an objective standard by which to measure the heat condition of any object or location. Now, I need not here go into the elementary phenomena or take up the elementary instruments for measuring heat. It must be assumed that you are acquainted with them. I will simply say that when the temperature condition is measured with a thermometer, there is a feeling that since we measure the degree above or below zero, we are getting an objective temperature measurement. In our thinking we consider that there is a fundamental difference between this objective determination in which we have no part and the subjective determination, where our own organization enters into the experience.

For all that the 19th century has striven to attain it may be said that this view on the matter was, from a certain point of view, fruitful and justified by its results. Now, however, we are in a time when people must pay attention to certain other things if they are to advance their way of thinking and their way of life. From science itself must come certain questions simply overlooked in such conclusions as those I have given. One question is this: Is there a difference, a real objective difference, between the determination of temperature by my organism and by a thermometer, or do I deceive myself for the sake of getting useful practical results when I bring such a difference into my ideas and concepts? This whole course will be designed to show why today such questions must be asked. From the principal questions it will be my object to proceed to those important considerations which have been overlooked owing to exclusive attention to the practical life. How they have been lost for us on account of the attention to technology you will see. I would like to impress you with the fact that we have completely lost our feeling for the real being of heat under the influence of certain ideas to be described presently. And, along with this loss, has gone the possibility of bringing this being of heat into relation with the human organism itself, a relation which must be all means be established in certain aspects of our life. To indicate to you in a merely preliminary way the bearing of these things on the human organism, I may call your attention to the fact that in many cases we are obliged today to measure the temperature of this organism, as for instance, when it is in a feverish condition. This will show you that the relation of the unknown being of heat to the human organism has considerable importance. Those extreme conditions as met with in chemical and technical processes will be dealt with subsequently. A proper attitude toward the relation of the unknown being of heat to the human organism has considerable importance. Those extreme conditions as met with in chemical and technical processes will be dealt with subsequently. A proper attitude toward the relation of the heat-being to the human organism cannot, however, be attained on the basis of a mechanical view of heat. The reason is, that in so doing, one neglects the fact that the various organs are quite different in their sensitiveness to this heat-being, that the heart, the liver, the lungs differ greatly in their capacity to react to the being of heat. Through the purely physical view of heat no foundation is laid for the real study of certain symptoms of disease, since the varying capacity to react to heat of the several organs of the body escapes attention. Today we are in no position to apply to the organic world the physical views built up in the course of the 19th century on the nature of heat. This is obvious to anyone who has an eye to see the harm done by modern physical research, so-called, in dealing with what might be designated the higher branches of knowledge of the living being. Certain questions must be asked, questions that call above everything for clear, lucid ideas. In the so-called “exact science,” nothing has done more harm than the introduction of confused ideas.

What then does it really mean when I say, if I put my fingers in the right and left hand vessels and then into a vessel with a liquid of an intermediate temperature, I get different sensations? Is there really something in the conceptual realm that is different from the so-called objective determination with the thermometer? Consider now, suppose you put thermometers in these two vessels in place of your fingers. You will then get different readings depending on whether you observe the thermometer in the one vessel or the other. If then you place the two thermometers instead of your fingers into the middle vessel, the mercury will act differently on the two. In the one it will rise; in the other it will fall. You see the thermometer does not behave differently from your sensations. For the setting up of a view of the phenomenon, there is no distinction between the two thermometers and the sensation from your finger. In both cases exactly the same thing occurs, namely a difference is shown from the immediately preceding conditions. And the thing our sensation depends on is that we do not within ourselves have any zero or reference point. If we had such a reference point then we would establish not merely the immediate sensation but would have apparatus to relate the temperature subjectively perceived, to such a reference point. We would then attach to the phenomenon just as we do with the thermometers something which really is not inherent in it, namely the variation from the reference point. You see, for the construction of our concept of the process there is no difference.

It is such questions as these that must be raised today if we are to clarify our ideas, or all the present ideas on these things are really confused. Do not imagine for a moment that this is of no consequence. Our whole life process is bound up with this fact that we have in us no temperature reference point. If we could establish such a reference point within ourselves, it would necessitate an entirely different state of consciousness, a different soul life. It is precisely because the reference point is hidden for us that we lead the kind of life we do.

You see, many things in life, in human life and in the animal organism, too, depend on the fact that we do not perceive certain processes. Think what you would have to do if you were obliged to experience subjectively everything that goes on in your organism. Suppose you had to be aware of all the details of the digestive process. A great deal pertaining to our condition of life rests on this fact that we do not bring into our consciousness certain things that take place in our organism. Among these things is that we do not carry within us a temperature reference point—we are not thermometers. A subjective-objective distinction such as is usually made is not therefore adequate for a comprehensive grasp of the physical.

It is this which has been the uncertain point in human thinking since the time of ancient Greeks. It had to be so, but it cannot remain so in the future. For the old Grecian philosophers, Zeno in particular, had already orientated human thinking about certain processes in a manner strikingly opposed to outer reality. I must call your attention to these things even at the risk of seeming pedantic. Let me recall to you the problem of Achilles and the tortoise, a problem I have often spoken about.

Let us assume we have the distance traveled by Achilles in a certain time \(a\). This represents the rate at which he can travel. And here we have the tortoise \(s\), who has a start on Achilles. Let us take the moment when Achilles gets to the point marked \(1\). The tortoise is ahead of him. Since the problem stated that Achilles has to cover every point covered by the tortoise, the tortoise will always be a little ahead and Achilles can never catch up. But, the way people would consider it is this. You would say, yes, I understand the problem all right, but Achilles would soon catch the tortoise. The whole thing is absurd. But if we reason that Achilles must cover the same path as the tortoise and the tortoise is ahead, he will never catch the tortoise. Although people would say this is absurd, nevertheless the conclusion is absolutely necessary and nothing can be urged against it. It is not foolish to come to this conclusion but on the other hand, it is remarkably clever considering only the logic of the matter. It is a necessary conclusion and cannot be avoided. Now what does all this depend on? It depends on this: that as long as you think, you cannot think otherwise than the premise requires. As a matter of fact, you do not depend on thinking strictly, but instead you look at the reality and you realize that it is obvious that Achilles will soon catch the tortoise. And in doing this you uproot thinking by means of reality and abandon the pure thought process. There is no point in admitting the premises and then saying, “Anyone who thinks this way is stupid.” Through thinking alone we can get nothing out of the proposition but that Achilles will never catch the tortoise. And why not? Because when we apply our thinking absolutely to reality, then our conclusions are not in accord with the facts. They cannot be. When we turn our rationalistic thought on reality it does not help us at all that we establish so-called truths which turn out not to be true. For we must conclude if Achilles follows the tortoise that he passes through each point that the tortoise passes through. Ideally this is so; in reality he does nothing of the kind. His stride is greater than that of the tortoise. He does not pass through each point of the path of the tortoise. We must, therefore, consider what Achilles really does, and not simply limit ourselves to mere thinking. Then we come to a different result. People do not bother their heads about these things but in reality they are extraordinarily important. Today especially, in our present scientific development, they are extremely important. For only when we understand that much of our thinking misses the phenomena of nature if we go from observation to so-called explanation, only in this case will we get the proper attitude toward these things.

The observable, however, is something which only needs to be described. That I can do the following for instance, calls simply for a description: here I have a ball which will pass through this opening. We will now warm the ball slightly. Now you see it does not go through. It will only go through when it has cooled sufficiently. As soon as I cool it by pouring this cold water on it, the ball goes through again. This is the observation, and it is this observation that I need only describe. Let us suppose, however, that I begin to theorize. I will do so in a sketchy way with the object merely of introducing the matter. Here is the ball; it consists of a certain number of small parts—molecules, atoms, if you like. This is not observation, but something added to observation in theory. At this moment, I have left the observed and in doing so I assume an extremely tragic role. Only those who are in a position to have insight into these things can realize this tragedy. For you see, if you investigate whether Achilles can catch the tortoise, you may indeed begin by thinking “Achilles must pass over every point covered by the tortoise and can never catch it.” This may be strictly demonstrated. Then you can make an experiment. You place the tortoise ahead and Achilles or some other who does not run even so fast as Achilles, in the rear. And at any time you can show that observation furnishes the opposite of what you conclude from reasoning. The tortoise is soon caught.

When, however, you theorize about the sphere, as to how its atoms and molecules are arranged, and when you abandon the possibility of observation, you cannot in such a case look into the matter and investigate it—you can only theorize. And in this realm you will do no better than you did when you applied your thinking to the course of Achilles. That is to say, you carry the whole incompleteness of your logic into your thinking about something which cannot be made the object of observation. This is the tragedy. We build explanation upon explanation while at the same time we abandon observation, and think we have explained things simply because we have erected hypotheses and theories. And the consequence of this course of forced reliance on our mere thinking is that this same thinking fails us the moment we are able to observe. It no longer agrees with the observation.

You will remember I already pointed out this distinction in the previous course when I indicated the boundary between kinematics and mechanics. Kinematics describes mere motion phenomena or phenomena as expressed by equations, but it is restricted to verifying the data of observation.

The moment we pass over from kinematics to mechanics where force and mass concepts are brought in, at this moment, we cannot rely on thinking alone, but we begin simply to read off what is given from observation of the phenomena. With unaided thought we are not able to deal adequately even with the simplest physical process where mass plays a role. All the 19th century theories, abandoned now to a greater or lesser extent, are of such a nature that in order to verify them it would be necessary to make experiments with atoms and molecules. The fact that they have been shown to have a practical application in limited fields makes no difference. The principle applies to the small as well as to the large. You remember how I have often in my lectures called attention to something which enters into our considerations now wearing a scientific aspect. I have often said: From what the physicists have theorized about heat relations and from related things they get certain notions about the sun. They describe what they call the “physical conditions” on the sun and make certain claims that the facts support the description. Now I have often told you, the physicists would be tremendously surprised if they could really take a trip to the sun and could see that none of their theorizing based on terrestrial conditions agreed with the realities as found on the sun. These things have a very practical value at the present, a value for the development of science in our time. Just recently news has gone forth to the world that after infinite pains the findings of certain English investigators in regard to the bending of starlight in cosmic space have been confirmed and could now be presented before a learned society in Berlin. It was rightly stated there “the investigations of Einstein and others on the theory of relativity have received a certain amount of confirmation. But final confirmation could be secured only when sufficient progress had been made to make spectrum analysis showing the behavior of the light at the time of an eclipse of the sun. Then it would be possible to see what the instruments available at present failed to determine.” This was the information given at the last meeting of the Berlin Physical Society. It is remarkably interesting. Naturally the next step is to seek a way really to investigate the light of the sun by spectrum analysis. The method is to be by means of instruments not available today. Then certain things already deduced from modern scientific ideas may simply be confirmed. As you know it is thus with many things which have come along from time to time and been later clarified by physical experiments. But, people will learn to recognize the fact that it is simply impossible for men to carry over to conditions on the sun or to the cosmic spaces what may be calculated from those heat phenomena available to observation in the terrestrial sphere. It will be understood that the sun's corona and similar phenomena have antecedents not included in the observations made under terrestrial conditions. Just as our speculations lead us astray when we abandon observation and theorize our way through a world of atoms and molecules, so we fall into error when we go out into the macrocosm and carry over to the sun what we have determined from observations under earth conditions. Such a method has led to the belief that the sun is a kind of glowing gas ball, but the sun is not a glowing ball of gas by any means. Consider a moment, you have matter here on the earth. All matter on the earth has a certain degree of intensity in its action. This may be measured in one way or another, be density or the like, in any way you wish, it has a definite intensity of action. This may become zero. In other words, we may have empty space. But the end is not yet. That empty space is not the ultimate condition I may illustrate to you by the following: Assume to yourselves that you had a boy and that you said, “He is a rattle-brained fellow. I have made over a small property to him but he has begun to squander it. He cannot have less than zero. He may finally have nothing, but I comfort myself with the thought that he cannot go any further once he gets to zero!” But you may now have a disillusionment. The fellow begins to get into debt. Then he does not stop at zero; the thing gets worse than zero. It has a very real meaning. As his father, you really have less if he gets into debt than if he stopped when he had nothing.

The same sort of thing, now, applies to the condition on the sun. It is not usually considered as empty space but the greatest possible rarefaction is thought of and a rarefied glowing gas is postulated. But what we must do is to go to a condition of emptiness and then go beyond this. It is in a condition of negative material intensity. In the spot where the sun is will be found a hole in space. There is less there than empty space. Therefore all the effects to be observed in the sun must be considered as attractive forces not as pressures of the like. The sun's corona, for instance, must not be thought of as it is considered by the modern physicist. It must be considered in such a way that we have the consciousness not of forces radiating outward as appearances would indicate, but of attractive force from the hole in space, from the negation of matter. Here our logic fails us. Our thinking is not valid here, for the receptive organ or the sense organ through which we perceive it is our entire body. Our whole body corresponds in this sensation to the eye in the case of light. There is no isolated organ, we respond with our whole body to the heat conditions. The fact that we may use our finger to perceive a heat condition, for instance, does not militate against this fact. The finger corresponds to a portion of the eye. While the eye therefore is an isolated organ and functions as such to objectify the world of light as color, this is not the case for heat. We are heat organs in our entirety. On this account, however, the external condition that gives rise to heat does not come to us in so isolated a form as does the condition which gives rise to light. Our eye is objectified within our organism. We cannot perceive heat in an analogous manner to light because we are one with the heat. Imagine that you could not see colors with your eye but only different degrees of brightness, and that the colors as such remained entirely subjective, were only feelings. You would never see colors; you would speak of light and dark, but the colors would evoke in you no response and it is thus with the perception of heat. Those differences which you perceive in the case of light on account of the fact that your eye is an isolated organ, such differences you do not perceive at all in the case of heat. They live in you. Thus when you speak of blue and red, these colors are considered as objective. When the analogous phenomenon is met in the case of heat, that which corresponds to the blue and the red is within you. It is you yourself. Therefore you do not define it. This requires us to adopt an entirely different method for the observation of the objective being of heat from the method we use of the objective being of light. Nothing had so great a misleading effect on the observers of the 19th century as this general tendency to unify things schematically. You find everywhere in physiologies a “sense physiology.” Just as though there were such a thing! As though there were something of which it could be said, in general, “it holds for the ear as for the eye, or even for the sense of feeling or for the sense of heat. It is an absurdity to speak of a sense physiology and to say that a sense perception is this or that. It is possible only to speak of the perception of the eye by itself, or the perception of the ear by itself and likewise of our entire organism as heat sense organ, etc. They are very different things. Only meaningless abstractions result from a general consideration of the senses. But you find everywhere the tendency towards such a generalizing of these things. Conclusions result that would be humorous were they not so harmful to our whole life. If someone says—Here is a boy, another boy has given him a thrashing. Also then it is asserted—Yesterday he was whipped by his teacher; his teacher gave him a thrashing. In both cases there is a thrashing given; there is no difference. Am I to conclude from this that the bad boy who dealt out today's whipping and the teacher who administered yesterday's are moved by the same inner motives? That would be an absurdity; it would be impossible. But now, the following experiment is carried out: it is known that when light rays are allowed to fall on a concave mirror, under proper conditions they become parallel. When these are picked up by another concave mirror distant form the first they are concentrated and focused so that an intensified light appears at the focus. The same experiment is made with so-called heat rays. Again it may be demonstrated that these too can be focused—a thermometer will show it—and there is a point of high heat intensity produced. Here we have the same process as in the case of the light; therefore heat and light are fundamentally the same sort of thing. The thrashing of yesterday and the one of today are the same sort of thing. If a person came to such a conclusion in practical life, he would be considered a fool. In science, however, as it is pursued today, he is no fool, but a highly respected individual.

It is on account of things like this that we should strive for clear and lucid concepts, and without these we will not progress. Without them physics cannot contribute to a general world view. In the realm of physics especially it is necessary to attain to these obvious ideas.

You know quite well from what was made clear to you, at least to a certain extent, in my last course, that in the case of the phenomena of light, Goethe brought some degree of order into the physics of that particular class of facts, but no recognition has been given to him.

In the field of heat the difficulties that confront us are especially great. This is because in the time since Goethe the whole physical consideration of heat has been plunged into a chaos of theoretical considerations. In the 19th century the mechanical theory of heat as it is called has resulted in error upon error. It has applied concepts verifiable only by observation to a realm not accessible to observation. Everyone who believes himself able to think, but who in reality may not be able to do so, can propose theories. Such a one is the following: a gas enclosed in a vessel consists of particles. These particles are not at rest but in a state of continuous motion. Since these particles are in continuous motion and are small and conceived of as separated by relatively great distance, they do not collide with each other often but only occasionally. When they do so they rebound. Their motion is changed by this mutual bombardment. Now when one sums up all the various slight impacts there comes about a pressure on the wall of the vessel and through this pressure one can measure how great the temperature is. It is then asserted, “the gas particles in the vessel are in a certain state of motion, bombarding each other. The whole mass is in rapid motion, the particles bombarding each other and striking the wall. This gives rise to heat.” They may move faster and faster, strike the wall harder. Then it may be asked, what is heat? It is motion of these small particles. It is quite certain that under the influence of the facts such ideas have been fruitful, but only superficially. The entire method of thinking rests on one foundation. A great deal of pride is taken in this so-called “mechanical theory of heat,” for it seems to explain many things. For instance, it explains how when I rub my finger over a surface the effort I put forth, the pressure or work, is transformed into heat. I can turn heat back into work, in the steam engine for instance, where I secure motion by means of heat. A very convenient working concept has been built up along these lines. It is said that when we observe these things objectively going on in space, they are mechanical processes. The locomotive and the cars all move forward etc. When now, through some sort of work, I produce heat, what has really happened is that the outer observable motion has been transformed into motion of the ultimate particles. This is a convenient theory. It can be said that everything in the world is dependent on motion and we have merely transformation of observable motion into motion not observable. This latter we perceive as heat. But heat is in reality nothing but the impact and collision of the little gas particles striking each other and the walls of the vessel. The change into heat is as though the people in this whole audience suddenly began to move and collided with each other and with the walls etc. This is the Clausius theory of what goes on in a gas-filled space. This is the theory that has resulted from applying the method of the Achilles proposition to something not accessible to observation. It is not noticed that the same impossible grounds are taken as in the reasoning about Achilles and the tortoise. It is simply not as it is thought to be. Within a gas-filled space things are quite otherwise than we imagine them to be when we carry over the observable into the realm of the unobservable. My purpose today is to present this idea to you in an introductory way. From this consideration you can see that the fundamental method of thinking originated during the 19th century, begins to fail. For a large part of the method rests on the principle of calculating from observed facts by means of the differential concept. When the observed conditions in a gas-filled space are set down as differentials in accordance with the idea that we are dealing with the movements of ultimate particles, then the belief follows that by integrating something real is evolved. What must be understood is this: when we go from ordinary reckoning methods to differential equations, it is not possible to integrate forthwith without losing all contact with reality. This false notion of the relation of the integral to the differential has led the physics of the 19th century into wrong ideas of reality. It must be made clear that in certain instances one can set up differentials but what is obtained as a differential cannot be thought of as integrable without leading us into the realm of the ideal as opposed to the real. The understanding of this is of great importance in our relation to nature.

For you see, when I carry out a certain transformation period, I say that work is performed, heat produced and from this heat, work can again be secured by reversal of this process. But the processes of the organic cannot be reversed immediately. I will subsequently show the extent to which this reversal applies to the inorganic in the realm of heat in particular. There are also great inorganic processes that are not reversible, such as the plant processes. We cannot imagine a reversal of the process that goes on in the plant from the formation of roots, through the flower and fruit formation. The process takes its course from the seed to the setting of the fruit. It cannot be turned backwards like an inorganic process. This fact does not enter into our calculations. Even when we remain in the inorganic, there are certain macrocosmic processes for which our reckoning is not valid. Suppose you were able to set down a formula for the growth of a plant. It would be very complicated, but assume that you have such a formula. Certain terms in it could never be made negative because to do so would be to disagree with reality. In the face of the great phenomena of the world I cannot reverse reality. This does not apply, however, to reckoning. If I have today an eclipse of the moon I can simply calculate how in time past in the period of Thales, for instance, there was an eclipse of the moon. That is, in calculation only I can reverse the process, but in reality the process is not reversible. We cannot pass from the present state of the earth to former states—to an eclipse of the moon at the time of Thales, for instance, simply by reversing the process in calculation. A calculation may be made forward or backward, but usually reality does not agree with the calculation. The latter passes over reality. It must be defined to what extent our concepts and calculations are only conceptual in their content. In spite of the fact that they are reversible, there are no reversible processes in reality. This is important since we will see that the whole theory of heat is built on questions of the following sort: to what extent within nature are heat processes reversible and to what extent are they irreversible?