Two philosophical traditions emerged from the legacy of Plato and Aristotle in a time of cultural, political, and military change. Epicureanism was the more elite of the two; Stoicism was more readily adaptable to the needs of ordinary people and to traditional Roman values. We encounter Zeno, the founder of Stoicism, and four later Roman Stoics: among them the philosopher-king Marcus Aurelius, who ruled with resolute virtue as emperor for 14 difficult years.