A philosophy tested by a slave, an emperor, and a senator facing execution. It held.Two thousand years ago, Epictetus was a slave who had his leg broken by a cruel master and became the most influential teacher of his age. Marcus Aurelius governed the Roman Empire through plague, war, and political chaos - and wrote private notes to himself that became one of the most widely read philosophical texts in history. Seneca navigated wealth, power, and an order from Nero...