The five hundred years from 300 B.C. to A.D. 200 were a period during which Greek science made spectacular advances and Greek philosophy underwent dramatic changes. How much did the scientists take note of the philosophical issues bearing on their pursuits? What progress did the philosophers make with methodological and theoretical issues arising out of developments in science? What influence did philosophical criticism or philosophical ideas have on specific theories in medicine or mechanics, mathematics or astronomy? These are some of the questions discussed in this series of papers by the distinguished scholars who took part in the Conference Hellenistique in Paris in 1980. The result is a broad-ranging and pioneering volume which will be of importance to scholars in the history and philosophy of science and to those whose interests lie in classical philosophy.