Histories of Philosophy typically include chapters on the period ‘from Thales to Plato’ which obscure the fact that Plato’s writings are the earliest extant in Greek philosophy. Most of our information about his predecessors dates from the Roman Empire, and is apt to receive the most uncritical treatment in such histories. At times the sources paraphrase, at other times they quote, but even then not with sufficient notice of the context to permit the redressing of error or prejudice in their interpretations. Philosophers quote their predecessors to illustrate the antiquity of their own opinions or, if the predecessor is unfriendly, to dispel the authority of his august name with such instruments as rhetoric can procure. If some readers were content with obloquy and ridicule, there were others whom citation, even if partial and unseasonable, was more likely to persuade.