Since the last book devoted exclusively to Philolaus was written by Boeckh in 1819, little apology seems necessary for presenting the scholarly world with a new commentary on his fragments and an interpretation of his philosophy. It is my hope that the present study will provide a basis on which Philolaus and early Pythagoreanism can enter the mainstream of scholarship both on the Presocratics and also on ancient philosophy as a whole. At present, despite the recent work of Schofield (KRS 1983), Barnes (1982), Nussbaum (1978), and Kahn (1974), it would appear that many scholars, at least tacitly, take the advice of Shorey which I print as an epigraph. They seem to feel that it is impossible to talk rigorously about the Pythagoreans in the way that we can about other Presocratics. “Pythagoreanism” seems to mean too much and to be hopelessly vague. The remedy for this problem is to focus detailed attention on the earliest Pythagorean texts we have, the fragments of Philolaus, and to use them as the foundation for our thinking about Pythagoreanism. It will be up to the reader to judge whether I have written any pages to which Shorey's dictum should not apply.

The giant on whose shoulders my work stands is Walter Burkert's magnificent Lore and Science in Ancient Pythagoreanism. Although I disagree with Burkert about the authenticity of a few fragments and although the interpretation of Philolaus' philosophy which I present is radically different from his, the reader will have a hard time finding a page on which I do not owe a debt to his work.