The Healers tells how people of different talents and intentions dealt with diseases and health. It tells how many of the greatest contributions to human health were made by people who did not prescribe pills or wield scalpels. Some had medical credentials, many did not. They were chemists, physicists, botanists, microbiologists, entomologists, engineers, psychologists, and people with a variety of other interests. Epidemics raged for centuries during which both victims and wanna-be healers were mired in imaginative superstitions about causes. Treatments generally were a mixed bag of remedies...