Rudolf Steiner:
"Future evolution must be prepared for. What man already produces from himself, as preparation for the future human being, is the word, speech. What man speaks remains in the Akashic Record. It is the germinal beginning for the future human being. Speech is one half of the former means of reproduction. Through speech man propagates himself spiritually. The breaking of the male voice is connected with this. One half of what is sexual has been carried over into speech. The voice is the future organ of reproduction. In ancient Hebrew the same word was used for sex and speech. Today man thinks, and the thought passes outwards through the larynx. The next stage will be that feeling, warmth, passes outwards. Then the word will be the expression of the inner warmth of the body. This can happen when the pituitary gland (hypophysis) develops in the brain. The stage following this appears when the pineal gland (epiphysis) is developed. Then not only the warmth-imbued word will go forth, but the word will remain, will be given form through the will, which then lives within it. Then when one utters the word it becomes an actual being.
Related to this is: ‘I think, I feel, I am’ (will). The word in this sense is ‘the word’ which undergoes a transformation from thinking into feeling and then into willing. This is a threefold process. First the word is ‘consciousness’ (in thinking), then ‘life’ (the warmth-permeated word), and lastly ‘form’, the word shaped through the will. This latter is the word become objective. So here too, following one another, we have: consciousness, life, form. Everything which today is form stems from earlier times and has arisen through such a process. The physical body, the form, is the most perfected body; less developed are the etheric body, life, and the astral body, consciousness."