Dustin Peone argues that memory is the foundation of philosophical thought. This may seem strange to the contemporary reader, but it is something that philosophers themselves have known since before Socrates. Peone advocates a doctrine of "memory as philosophy" that ties philosophical recollection back to the wisdom of the Muses, daughters of Memory, who sing of "what was, is, and shall be." Part One draws on the work of philosophers from Cicero to Vico to Bergson to articulate the meaning and significance of memory. Peone understands memory not merely in its psychological sense, but as the key to metaphysical and moral thinking. Part Two takes up the philosophical history of memory. Peone gives an overview of its role as both a speculative and technical instrument from ancient Greece through Renaissance Europe. Then with the rise of modernity and the critical philosophy of Descartes, the memory tradition falls into disrepute. Why did this happen? Was it accidental? Is a philosophical system grounded in memory possible after Descartes? In the final chapters, Montaigne and Hegel are analyzed as practitioners of "memory as philosophy" in the modern world.