Anaximander offered one theory of the world, the Greek atomists another. Both seem hopelessly inadequate today. Anaximander was wrong about the shape of the earth; the atomists were wrong about ‘atoms’ being solid and indivisible. But what is it for them to be wrong? What would it be to be right, is that the same as the theory being true? What is truth? In this chapter and the next I will introduce some attempts to answer those questions.