• Interpretations of the Theaetetus digression fail to see how it functions in Plato’s argument because they have taken its praise of the philosopher at face value. But this is not the philosopher from Republic. His otherworldliness reflects both Theodorus’ mathematical understanding of philosophy as the study of ‘divine’ objects and the judgement of the man of the law courts that philosophy renders a man useless for the city’s business. In spite of how appealing interpreters have found it, Socrates’ mythological language shows that the philosopher is an enigma to the practical man. That is why Socrates must appeal to the practical knowledge of the crafts to refute the relativism of opinion that he had to put forward in Protagoras’ defence.