Nicomachean Ethics – Aristotle

"One swallow does not make a summer, neither does one fine day."

Aristotle asks the fundamental question: what is the best life for a human being? He argues that the goal of all human action is 'eudaimonia' (flourishing or happiness), which is achieved through the practice of virtue. He defines virtue as a 'mean' between two extremes (e.g., courage is between cowardice and rashness) and emphasizes the importance of friendship and contemplation.

This work is the cornerstone of virtue ethics. Unlike modern moral theories based on rules or consequences, Aristotle focuses on character and the cultivation of good habits. It remains one of the most practical and influential guides to living a good life.