370. It is to be observed that the very forms of man's members, organs, and viscera, as regards the structure itself, are from fibers that arise out of their first principles in the brains; but these become fixed by means of such substances and matters as are in earths, and from earths in air and in ether. This is effected by means of the blood. Consequently, in order that all parts of the body may be maintained in their formation and rendered permanent in their functions, man requires to be nourished by material food, and to be continually renewed.