VIII. Man's First Ancestors

Obviously, the whole process of the evolution of man has hitherto been connected with the alteration in the degree of warmth of our earth; it was, in fact, due to the heat in his surroundings that man evolved to the stage we have just described. The heat from without, however, had now reached a point at which further progress in the formation of the human body was no longer possible. Thus, with the cooling off of the earth, a corresponding reaction set in within the form itself, and man became the generator of his own supply of heat, whereas hitherto his temperature had been that of his surroundings. Organs now appear in him, enabling him to generate for himself the degree of heat necessary for his life. Up till now, currents of substances had circulated within him, dependent on the environment for the necessary heat; but now he could generate his own heat, for these substances and the fluids of the body turned into warm blood. Thus he had attained a far greater degree of self-dependence as a physical being than ever before, and his whole inner life was intensified. Sensation still depended entirely upon the effects of the outer world. The filling of the body with its own warmth gave it an independent physical inner life. The soul had now a field of activity within the body, where it could unfold an existence which would no longer be a mere sharing in the life of the outer world.