Epictetus on What We Control
"Some things are up to us and some are not." — Epictetus cracks open the door to Stoic sanity: «Τῶν ὄντων τὰ μὲν ἐφ' ἡμῖν, τὰ δὲ οὐκ ἐφ' ἡμῖν.»

Unknown — "Marble calyx-krater with reliefs of maidens and dancing maenads" (1st century CE), public domain
The ultimate Stoic boundary.
Epictetus opens his Enchiridion (1.1) with: «Τῶν ὄντων τὰ μὲν ἐφ' ἡμῖν, τὰ δὲ οὐκ ἐφ' ἡμῖν.» — «Some things are up to us and some are not.» In a single line, he sketches the Stoic worldview: control what you can, accept what you can’t.
Freedom through focus.
For Epictetus, anxiety comes from mixing up these categories — raging at weather, fate, or the actions of others, instead of steering your own choices. The Stoic cure: put your energy where you have power. Let the rest blow by like Mediterranean wind.
From slave to philosopher.
Epictetus was born a slave, owned nothing, and limped through life. Yet his calm, sharp logic about control inspired emperors and prisoners alike. His advice is evergreen: don’t chain your happiness to what you can’t command.
Epictetus drew the line between what we can change and what we can’t — the Stoic distinction that still keeps people sane in a chaotic world.