Contradicting the long-held belief that Aristotle was the first to discuss individuation systematically, Mary Margaret McCabe argues that Plato was concerned with what makes something a something and that he solved the problem in a radically different way than did Aristotle. McCabe explores the centrality of individuation to Plato's thinking, from the Parmenides to the Politicus, illuminating Plato's later metaphysics in an exciting new way. Tradition associates Plato with the contrast between the particulars of the sensible world and transcendent forms, and supposes that therein lies the center of Plato's metaphysical universe. McCabe rebuts this view, arguing that Plato's thinking about individuals--which informs all his thought--comes to focus on the tension between generous or complex individuals and austere or simple individuals. In dialogues such as the Theaetetus and the Timaeus Plato repeatedly poses the question of individuation but cannot provide an answer. Later, in the Sophist, the Philebus, and the Politicus, Plato devises what McCabe calls the mesh of identity, an account of how individuals may be identified relative to each other. The mesh of identity, however, fails to explain satisfactorily how individuals are unified or made coherent. McCabe asserts that individuation may be absolute--and she questions philosophy's longtime reliance on Aristotle's solution.