This volume tells one side of the story of ancient Greek cosmology, and takes it as far as the criticisms directed by Aristotle at his materialistic predecessors. The book is to be completed in a second volume, The Teleological World Picture and its Opponents. In that I shall give an account of the cosmology of Plato's Timaeus and Aristotle's works on the philosophy of nature, followed by the attempted rehabilitation of the atomic theory of the universe by Epicurus and his followers. Then I shall try to describe the arguments of philosophers of the Hellenistic period and later, including the Stoics and the later Peripatetics. I hope to take the story as far as the time of Simplicius and Philoponus, in the sixth century A.D.

I have tried to make the book readable by those with no specialized knowledge of Greek philosophy, and no Greek. Although it is not designed to be a course textbook, in writing it I have kept in mind the students to whom I lecture every year in Princeton University in a course called ‘Introduction to Ancient Philosophy’. They include some who are taking a major in Classics or Philosophy, but also many who have never before studied the ancient world or read anything of the Greek philosophers. I have tried to keep the philological technicalities to a minimum.

On some subjects I have adopted positions that need more detailed defense than I have been able to give in this context. I have sometimes argued the case in articles that have been published separately in the professional journals, or in papers that are not yet published.