Hippocrates (fifth century B.C.), semilegendary Greek physician from Cos. Some sixty treatises survive under his name, but it is doubtful whether he was the author of any of them. The Hippocratic corpus contains material from a wide variety of standpoints, ranging from an extreme empiricism that rejected all grand theory (On Ancient Medicine) to highly speculative theoretical physiology (On the Nature of Man, On Regimen). Many treatises were concerned with the accurate observation and classification of diseases (Epidemics) rather than treatment. Some texts (On the Art) defended the claims of medicine to scientific status against those who pointed to its inaccuracies and conjectural status; others (Oath, On Decorum) sketch a code of professional ethics. Almost all his treatises were notable for their materialism and rejection of supernatural ‘explanations’; their emphasis on observation; and their concern with the isolation of causal factors. A large number of texts are devoted to gynecology. The Hippocratic corpus became the standard against which later doctors measured themselves; and, via Galen’s rehabilitation and extension of Hippocratic method, it became the basis for Western medicine for two millennia. R.J.H.