The soul is subject to health and disease, just as is the body. The health and disease of both... undoubtedly depend upon beliefs and customs, which are peculiar to mankind.
Medical practice is not knitting and weaving and the labor of the hands, but it must be inspired with soul and be filled with understanding and equipped with the gift of keen observation . . .
The soul, when accustomed to superfluous things, acquires a strong habit of desiring things which are neither necessary for the preservation of the individual nor for that of the species. This desire is without limit, whilst those which are necessary are few in number and restricted within certain limits; but what is superfluous is without end.