Diseases spring from the disturbance of the original elements of which our bodies are composed; and the soul also suffers from two mental distempers—madness and ignorance. As far as possible, nature should be left to herself; but since there is a strong sympathy between soul and body, the conditions of health in both must be observed; the limbs should be trained by exercise, and the mind should be educated by music and philosophy. For no man can prolong his life beyond a certain time; and medicines ignorantly administered multiply diseases and destroy the constitution.
Man should exercise in due proportion the three souls implanted in him, more especially that highest and divinest element in our heads, which makes us look upward like plants, and draws our thoughts from earth to heaven. If he seeks wisdom and truth, then he "must of necessity, so far as human nature is capable of attaining immortality, become all immortal, as he is ever serving the divine power, and having the genius that dwells in him in the most perfect order, his happiness will be complete." But if he gratifies ambition and desire, he will degenerate into a merely mortal being, and after this life will lose his high place in creation, first passing into the form of a woman, and then into the still lower form of an animal; for animals are only deteriorated humanity—the birds being "innocent and light-minded men," who thought in their simplicity that sight alone was needed to know the truths of celestial regions; and the quadrupeds and wild animals being all more or less brutal and
