Donald L. M. Baxter's meticulous attention to textual detail yields a highly original interpretation of some of the most neglected or maligned parts of Hume's "Treatise". The focus is Hume's treatment of the concept of numerical identity, which is central to his famous discussions of the external world and personal identity. Hume raises a long unappreciated, and still unresolved, difficulty with the concept of identity: how to represent something as "a medium betwixt unity and number." Superficial resemblance to Frege's famous puzzle has kept the difficulty in the shadows. Hume's way of addressing it makes sense only in the context of his unorthodox theory of time. Baxter shows the defensibility of that theory against past dismissive interpretations, especially of Hume's stance on infinite divisibility. Later the author shows how the difficulty underlies Hume's later worries about his theory of personal identity, in a new reading motivated by Hume's important appeals to consciousness. Baxter casts Hume throughout as an acute metaphysician, and reconciles this side of Hume with his overarching Pyrrhonian skepticism. The book will be useful to those interested in the metaphysics of identity and time, and the epistemology of metaphysics, and will be indispensable to Hume scholars, who have lacked an in-depth treatment of these crucial and intricate issues. It is the first, focused study of Hume on time and identity.