This collection of papers, half of which were given at the series of seminars on Stoicism at the Institute of Classical Studies of the University of London in 1967-8, discusses topics which are of central importance in Stoic philosophy. The Greek Stoics made notable contributions to logic, metaphysics, theory of knowledge and ethics which justify more attention than they have received, and the present work offers a detailed analysis of theories which exhibit the Stoics' philosophical significance and originality. Each chapter is self-contained but by their different styles of approach and interpretation the six authors are able to demonstrate much of the coherence and some basic difficulties of Stoicism.