In chapter 2 we have already taken a preliminary look at Plato's first observations on the cosmology of his predecessors. He gave us an unforgettable picture of Socrates reviewing his life of philosophizing, as he sat in prison with friends on the last day of his life. The main target of his criticism of earlier philosophy was its neglect of the question ‘to what end?’ or ‘what is the good of this?’ The physicists gave him nothing but a story of matter in motion, of how, not why, things come to be as they are. This Socrates found so unsatisfying that he turned to a quite different kind of philosophy.

Plato returned to criticism of materialism in works written later than Phaedo, and that is the subject of this chapter. First we must observe that Plato seldom names the targets of his criticism. Of the ‘physicists’ we have reviewed in earlier chapters, Plato mentions Thales, but not Anaximander or Anaximenes; Anaxagoras several times, but Empedocles only twice; and Leucippus and Democritus not at all. The omission of the last two has surprised the commentators from ancient times to the present day. There is a story in the biography of Democritus in Diogenes Laertius (ix.40) that Plato wanted to burn all of Democritus' books that he could collect, but was prevented by two Pythagoreans. It was no use, they said, the books were too widely published.