His name was not Epictetus. Epictetus means the acquired one — the purchased property. His actual name is lost. He was brought to Rome as a slave and assigned to Epaphroditus, a secretary of Emperor Nero, who was himself a freed slave and who treated his own slaves with the specific cruelty of the recently liberated.
Epaphroditus wanted to demonstrate something — perhaps to a guest, perhaps to a group of other slaves. He took Epictetus's leg and began to twist it.
Epictetus said quietly: you are going to break it.
Epaphroditus twisted harder.
Epictetus said: I told you so. You see — it is broken.
There are different versions of this story. In some, Epictetus smiles throughout. In all versions, he is calm — not performing calm, not suppressing a scream, but genuinely indifferent to the breaking of his leg in a way that was not indifference to pain but indifference to the specific suffering that comes from wanting circumstances to be other than they are.
The leg was going to break whether he screamed or not. Screaming would not have saved it. Rage at Epaphroditus would not have saved it. The only question was what he did with his inner state during the breaking — and his inner state was his. His master had his body. His master had his freedom of movement and his capacity for self-determination in the external world. His master did not have the one thing Epictetus had identified as the only thing that was genuinely his: the quality of his response to what was happening to him.
The Stoic distinction between ta eph' hēmin — what is up to us — and ta ouk eph' hēmin — what is not up to us — is the entire philosophical system compressed into a single observation. What is up to us: our judgments, our impulses, our desires, our responses. What is not up to us: our bodies, our reputations, our positions, others' opinions of us, the external circumstances of our lives. Epictetus had tested this distinction in the most extreme available conditions and found it accurate. The leg was not up to him. His response was. The slave had less external freedom than almost any person in Rome. He was, by the measure of the only freedom the Stoics considered real, one of the freest.
He was eventually freed — whether by Epaphroditus or by another means is unclear. He became a teacher. Students came from across the empire to learn from him — wealthy students, powerful students, people whose external circumstances were infinitely better than his had been and who were, by his measure, significantly less free.
He taught from a rented room with a straw mat and an iron lamp. When the lamp was stolen — his only possession — he replaced it with an earthen one and observed that the thief had done him a service: now he had something less worth stealing.
The Enchiridion — the handbook of his teachings — was compiled by his student Arrian, who wrote it from notes because Epictetus refused to write it himself. He had said everything he had to say in the classroom. Whatever was left was the student's to discover.
The leg never healed properly. Epictetus walked with a limp for the rest of his life. There is no record of him ever mentioning it.