Human lives are full of pleasures and pains. And humans are creatures that are able to think: to learn, understand, remember and recall, plan and anticipate. Ancient philosophers were interested in both of these facts and, what is more, were interested in how these two facts are related to one another. There appear to be, after all, pleasures and pains associated with learning and inquiring, recollecting and anticipating. We enjoy finding something out. We are pained to discover that a belief we hold is false. We can think back and enjoy or be upset by recalling past events. And we can plan for and enjoy imagining pleasures yet to come. This book is about what Plato, Aristotle, the Epicureans and the Cyrenaics had to say about these relationships between pleasure and reason.