This chapter explores Aristotle’s intellectual development, methodological distinctiveness, and ethical thought, particularly as expressed in the Nicomachean Ethics. It begins with an account of Aristotle’s biography, including his long association with Plato, his departure from Athens, and the eventual founding of his own school, the Lyceum. A crucial distinction is drawn between the genres of Platonic and Aristotelian texts: Plato’s dialogues are literary-philosophical compositions, while Aristotle’s surviving works are mostly lecture notes. The chapter argues that this difference in genre has shaped interpretive traditions. Central to Aristotle’s ethics is the idea that observation of human life, rather than abstract theorizing, grounds our understanding of the good. Ethics, he argues, must be treated with appropriate imprecision due to its practical and variable subject matter. Happiness (eudaimonia), for Aristotle, is not pleasure or honor but a life of activity in accordance with virtue, achieved through habituation and deliberate choice. Virtue is conceived as a mean between extremes and guided by phronêsis (practical wisdom). The chapter concludes by emphasizing Aristotle’s belief in the divine dimension of human flourishing and his view that ethics, properly understood, is inseparable from civic life and human interrelation within the polis.