Nor can we ever hope to ward death off by keeping the tissues of the body young and growing to the end of life and breaking the law, to which nearly all species are subject, of attaining their maximum size long before age and decline set in. It has long been realized that one of the first signs of the advent of the chronic hereditary diseases in children is the arrest of growth but man can never, of course, hope to approximate immortality by attaining gigantic size. Nor can we hope to advance toward the old idea of macrobiotism by permanently lowering the temperature within the body, as experimenters show can be done with great increase of life for certain of its lower forms, especially those called cold-blooded which take the temperature of the medium in which they live. And yet here man has a very old instinct, reinforced by modern hygiene, to avoid excessive heat, an instinct that perhaps originally impelled him to leave tropic regions and haunt the edge of retreating glaciers. Nor can we ever expect to rejuvenate man by bringing about a dedifferentiation of organs or functions because just this is the price we pay for progress, evolution, and individuation. But this concept, too, has many prelusive forms in the early developmental history of human consciousness and it has its own obvious anagogic meaning. If we follow these trends they lead us, of course, straight to Pantheism and give us a painful sense of the limitations inherent in personality itself. As to the conclusion of Loeb, that life departs with breath because the absence of a fresh supply of oxygen lets loose dissolutive chemical changes its presence prevented, the pragmatic layman can only point to the recognition that in a few generations has become world-wide, of the value of ventilation, deep breathing, and the adequate oxidation of tissues. This shows that man felt that life was closely bound up with oxygen long before he could prove it. So the biological evidence that it is the brain or nervous system that dies first and determines the death of all the other parts and functions, if it has any culture correlate, finds it probably in the hazy quarter truths of the doctrines of the mental healers, that far more human ills and far more deaths and preventions and postponements of death than we know are amenable to mind cure because they are mind-made.