This book began life in my final two years at Yale, and then grew to completion during the past six years at Georgetown. Its conception, however, was even earlier, for as I wrote the Fabric of Character, Kant's voice insistently pressed for inclusion in the discussion. It took many years to shape the conversation Kant would come to have with Aristotle. The themes I have settled on are those that I think are central to the debate, though by no means exhaustive. As readers will see, the debate is a reconstructed one. Careful attention is paid to the details of texts, but with an eye toward creating a shared discourse rather than a mapping of actual lines of transmission and debt. The felt need to bring Aristotle and Kant together in conversation has, of course, not been mine alone. With the flourishing of studies in the history of moral philosophy, others too have found points of intersection and contrast, which were often obscured in earlier, overly neat categorizations. I have profited from this general resurgence in history of philosophy studies as well as from the shifting interest in normative ethics toward taking a more serious look at texts and the complex stories they have to tell. In ancient ethics, I have learned enormously from the recent work of Julia Annas and Martha Nussbaum, and in Kantian studies, from Barbara Herman and Onora O'Neill's pioneering work.