Stoicism was a school of philosophy founded in Athens around 300 BC by Zeno of Citium. Key figures: Epictetus, Marcus Aurelius, Seneca.
**Core beliefs:**
1. **The dichotomy of control:** Some things are "up to us" (our thoughts, judgments, desires) and some are not (health, wealth, others' opinions). Happiness comes from focusing only on what we control.
2. **Virtue is the only good:** External things (money, status, health) are "preferred indifferents" — nice to have but not necessary for a good life. Virtue (wisdom, justice, courage, temperance) is the only true good.
3. **Live according to nature:** Humans are rational beings; living rationally and virtuously is living according to our nature.
4. **Emotions come from judgments:** Negative emotions arise from false beliefs. "Men are disturbed not by things, but by their opinions about things." — Epictetus
**Still relevant today:** CBT (cognitive behavioral therapy) is heavily influenced by Stoicism.