Epictetus

Epictetus was born a slave in Hierapolis, in what is now Turkey; even his name is not a name — epiktetos means 'acquired.' He was owned by Epaphroditus, a powerful freedman at Nero's court, and he was lame. One ancient story says his master twisted his leg until it broke while Epictetus calmly predicted the result; a drier source blames rheumatism. Either way he walked through life on a crutch, and treated the leg as his standing example of what is not up to us.

While still enslaved he was permitted to study with Musonius Rufus, and after gaining his freedom he taught in Rome — until the emperor Domitian banished the philosophers. Epictetus moved to Nicopolis, on the western coast of Greece, and built the most famous school in the Roman world. He owned a mat, a lamp, and little else; when someone stole the iron lamp, he replaced it with a clay one. Late in life, unmarried and ascetic, he took in an infant who would otherwise have been abandoned, and raised the child with a woman's help.

He wrote nothing. His student Arrian transcribed the classroom sessions that became the Discourses and distilled them into the Enchiridion — the 'handbook.' Its first sentence is the most consequential sorting rule in ancient philosophy: some things are within our power, and some are not. Half a century after his death, the most powerful man alive — Marcus Aurelius — was studying a copy of the Discourses and taking notes.