The second thing which man teaches himself, and that by means of the entity which proceeds from one incarnation to another as the same being, is speech. Through speech he comes into relation with his fellow-men. This relation makes him the vehicle of that spiritual life which interpenetrates the world primarily through man. Emphasis has often been laid, with good reason, on the fact that a human being removed, before he could speak, to a desert island, and kept apart from his fellows, would not learn to talk. On the other hand, what we receive by inheritance, what is implanted in us for use in later years and is subject to the principles of heredity, does not depend on a man’s dwelling with his fellows. For instance, his inherited conditions oblige him to change his teeth in his seventh year. If it were possible for him to grow up on a desert island, he would still change them then. But he only learns to talk, when his soul’s inner being, i.e., that which is carried on from one life to another, is stimulated. The germ, however, for the development of the larynx must be formed during the period at which man has not yet acquired his ego-consciousness. Before the time to which his memory goes back, he must plant the germ for developing his larynx, in order that this may become the organ of speech. And then there is a third thing: It is not so well known that man learns this of himself, from that part of his inner being which he carries on from one incarnation to another. It is the life within the world of thought itself. The elaboration of the brain is undertaken because the brain is the instrument of thought. At the beginning of life, this organ is still plastic, because the individual has to form it for himself as an instrument of thought, in accordance with the intention of the entity which is carried on from one life to another. The brain immediately after birth is, as it was bound to be, in accordance with the forces inherited from parents and other ancestors. But the individual has to express in his thought what he is as an individual being, in accordance with his former earthly lives. Therefore he must re-model the inherited peculiarities of his brain, after birth, when he has become physically independent of his parents and other ancestors.