In this volume--the first, focused study of Hume on time and identity--Baxter focuses on Hume's treatment of the concept of numerical identity, which is central to Hume's 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...