Lecture VIII

We know that man's astral body consists of two parts: one part upon which he has as yet done nothing, which is therefore as it was macrocosmically, and one part upon which he has worked. These two parts are in a certain way developed in everyone. In the higher nerve system, particularly in the brain which is built afresh with each new incarnation, you have the material expression of the work done by man's ego upon his astral body. Thus man has a much more completely developed forebrain than the animal because the front part of the brain is the manifestation of the astral body worked upon by the ego. But the astral body has nevertheless its outer expression in the nerve system as well.