Aristotle's 'Nicomachean Ethics' defines the good life as achieving eudaimonia through rational activity and virtue, emphasizing that happiness arises from virtuous actions alongside friends. The text contrasts various ethical theories, addressing the nature of virtue, moral development, justice, and the relationship between self-love and friendship. Ultimately, Aristotle posits that moral fulfillment aligns with rationally guided choices, necessitating a balance between personal desires and moral responsibilities.