The ancient Greek philosopher Epicurus (341-271/0 BCE) has attracted much contemporary interest. Tim O'Keefe argues that the sort of freedom which Epicurus wanted to preserve is significantly different from the 'free will' which philosophers debate today, and that in its emphasis on rational action, has much closer affinities with Aristotle's thought than with current preoccupations. His original and provocative book will be of interest to a wide range of readers in Hellenistic philosophy.