Rudolf Steiner, March 26, 1910:
These different members of man's organism and constitution [the physical body, the etheric body, the astral body, and the ego] have been formed out of different spiritual worlds. To understand this we shall do well to remind ourselves of a beautiful, profoundly wise saying of Goethe: “The eye is formed by the light for the light.” [* See Goethe's Studies in Natural Science. (Kürschner, Nationalliteratur, Vol. 35, p. 88). “The eye owes its existence to the light. Out of indifferent animal organs the light produces an organ to correspond to itself; and so the eye is formed by the light for the light so that the inner light may meet the outer.”] Schopenhauer, and Kant too, want to present the whole world as man's idea; this philosophy seeks to emphasise that without an eye we should perceive no light, that without an eye there would be darkness around us. That, of course, is true, but the point is that it is a one-sided truth. Unless the other side is added a one-sided truth is being regarded as the whole truth — than which there is nothing more pernicious. To say something that is incorrect is not the worst thing that can happen, for the world itself will soon put one right about it; but it is really serious to regard a one-sided truth as the absolute truth and to persist in so regarding it. That without the eye we could see no light is a one-sided truth. But if the world had remained forever filled with darkness, we should have had no eyes. When animals have lived for long ages in dark caves they lose their sight and their eyes go to ruin. On the one side it is true that without eyes we could gee no light, but on the other side it is equally true that the eyes have been formed by the light, for the light. It is always essential to look at truths not only from the one side but also from the other. The fault of most philosophers is not that they say what is false — in many cases their assertions cannot be refuted because they do state truths — but that they make statements which are due to things having been viewed from one side only. If you take in the right sense the saying that “the eye is formed by the light, for the light”, you will be able to say to yourselves that there must be something in the light that admittedly we do not see with our eyes but that has developed the eyes out of an organism which at first had no eyes. Behind the light there is something hidden. Let us say here: The eye-forming power is contained in every ray of sunlight. From this we can realise that everything round about us contains the forces which have created us. Just as our eyes are created by something within the light, all our organs have been formed by something that underlies everything we see in the world outside as external surfaces only.
Now man also has intellect, intelligence. In physical life he is able to use his intelligence because he has an instrument for it. Remember, we are speaking now of the physical world, not of what becomes of our thinking when we are free of the body after death, but of how we think through the instrument of the brain when we have wakened from sleep in the morning; after waking we see light through the eyes. In the light there is something that has formed the eye. We think through the instrument of the brain; thus there must be something in the world that has formed the brain in such a way that it could become an instrument of thinking suitable for the physical world. The brain has been made into an organ of thinking for the physical world by the power which manifests externally in our intelligence. Just as the light we perceive with the eye is an eye-forming power, our brain is the surface manifestation of a brain-forming power or force. Our brain is formed from out of the World of Spirit.
One who has attained Initiation recognises that if only the Elementary World and the World of Spirit existed, man's organ of intelligence could never have come into being. The World of the Spirit is indeed a lofty world but the forces which have formed the physical organ of thinking must have streamed into man from a yet higher world in order that intelligence might manifest outwardly, in the physical world.