This book offers a solution to the ancient philosophical problem regarding the nature and the justification of morality. The importance of this subject matter is obvious, not merely as an abstract philosophical problem, but perhaps even more as a practical challenge, regarding the way we ought to live our lives: the values that ought to direct us, and the ends that we ought to pursue. In the course of this inquiry, a wide array of philosophical topics is explored: the nature of intentional action, and the role played by reason and desires in agency; the question of the final end of agency – better known in ancient terminology as the question of the purpose of life, and in modern terms as the question of the meaning of life; the nature of moral obligations and their rational justification; the challenge posed by determinism for the freedom of the will, with its implications on fatalism and moral responsibility; and normative questions regarding the value of life. This book is of interest not only to professional philosophers, but also to any intellectual who is concerned with questions about morality, our nature as agents, and the end that we ought to pursue.