This collection of new essays explores the complex and contested histories of drugs and narcotics in societies from ancient Greece to the present day. The Greek term pharmakon means both medicament and poison. The book shows how this verbal ambivalence encapsulates the ambiguity of man's use of chemically-active substances over the centuries to diminish pain, fight disease, and correct behaviour. It shows that the major substances so used, from herbs of the field to laboratory-produced synthetic medicines, have a healing potential, and have been widely employed both within and outside the medical profession.