John Palmer presents a new and original account of Plato's uses and understanding of his most important Presocratic predecessor, Parmenides. Adopting an innovative approach to the appraisal of intellectual influence, Palmer first explores the Eleatic underpinnings of central elements in Plato's middle-period epistemology and metaphysics and then shows how in the later dialogues Plato confronts various sophistic appropriations of Parmenides.