In 1933-34, I took a full-blown college course on the University of Chicago campus. This was part of an experiment by President Hutchins to see wheth… - William Hardy McNeill

The diffusion of alchemy westward, like the movement of astrology eastward, became significant only in the centuries after 200 A.D. The conservatism of learning was such that, even when commercial intercourse had made intellectual contacts possible, little serious interchange took place until severe social stress had disturbed the even tenor of the times in China, India, and Europe. Technology was a little, but only a little, less conservative.

Ever since language allowed human cultural evolution to impinge upon age-old processes of biological evolution, humankind has been in a position to upset older balances of nature in quite the same fashion as disease upsets the natural balance within a host's body. Time and again, a temporary approach to stabilization of new relationships occurred as natural limits to the ravages of humankind upon other life forms manifested themselves. Yet, sooner or later, and always within a span of time that remained miniscule in comparison with the standards of biological evolution, humanity discovered new techniques allowing fresh exploitation of hitherto inaccessible forms of life.

The practical basis of the medical profession rested on psychology. Everyone felt better when self-confident, expensive experts could be called in to handle a vital emergency. Doctors relieved others of the responsibility for deciding what to do. As such, their role was strictly comparable to that of the priesthood, whose ministrations to the soul relieved anxieties parallel to those relieved by medical ministrations to the body.