Aristotle made a groundbreaking shift in classical thought by arguing that happiness, or eudaimonia, is the ultimate goal (telos) of human life and that it "depends on ourselves." He was the first to make human flourishing the central focus of ethics. Interestingly, his contemporary in China, Mencius, independently arrived at a similar idea: that flourishing requires the cultivation of virtue.

However, their views diverged on the nature of that virtue. For Mencius, virtue was inseparable from social and political roles. For Aristotle, while expressed within a community, virtues were fundamentally about perfecting the individual's character.

Crucially, Aristotle did not see happiness as a purely internal state. He insisted that a flourishing life is also dependent on external conditions like good health, friends, and adequate resources. By combining a person's internal state with their external circumstances, Aristotle effectively created a framework for a "science of happiness." This isn't a modern, empirical science, but a classical epistēmē: a systematic body of knowledge focused on understanding the purpose of a human life.