The core: what's yours and what isn't
“Some things are within our power, and some things are not.” Enchiridion 1, the opening line of the handbook and the whole system in eleven words: opinions, aims, and actions are yours; bodies, reputations, and outcomes aren't. “Men are disturbed not by things, but by the views they take of things.” Enchiridion 5, the sentence cognitive-behavioral therapy's founders explicitly credited; the modern “it's not what happens to you, but how you react” is a paraphrase of this.
On practice over talk
“Don't explain your philosophy. Embody it” is the internet's compression of Enchiridion 46, where the original is better: sheep don't vomit up their grass to show the shepherd how much they've eaten; they digest it and produce wool and milk. Show your principles the same way. “How long are you going to wait before you demand the best for yourself?” Enchiridion 51, the handbook's closing shove: you know the principles; the postponement is the problem. “It is impossible for a man to learn what he thinks he already knows.” Discourses II.17, the tuition fee for every beginner's mind.
On wanting less
“Wealth consists not in having great possessions, but in having few wants.” Preserved via the ancient fragment collections (Stobaeus) rather than the Discourses proper; genuinely ancient attribution, worth the small asterisk. “He is a wise man who does not grieve for the things which he has not, but rejoices for those which he has” travels under his name with softer sourcing; the sentiment is his, the sentence likely later. The pattern deserves its own note: Epictetus published nothing; everything survives through his student Arrian's transcripts, so 'sourced' always means 'as recorded.'
Where he fits, and where to keep him
Epictetus is the demanding end of the Stoic shelf: Seneca charms, Marcus soothes, Epictetus tells you to stop whining and start now (the reading order saves him for when you're invested; the three-Stoic quote guide puts them side by side). The Enchiridion is an hour's read and free in public domain. For the daily-dose version with the whole tradition around him: 365 Days of Philosophy, one sourced page a day, and the free daily philosophy email costs nothing to try.
Common questions
What is Epictetus' most famous quote?
Enchiridion 5: 'men are disturbed not by things, but by the views they take of things,' the line CBT's founders credited, with Enchiridion 1's 'some things are within our power, and some are not' as the system's opening move.
Did Epictetus write any books?
No; he taught orally, and his student Arrian transcribed the Discourses and compressed them into the Enchiridion (the 'handbook'). Every Epictetus quote is therefore 'as recorded,' which explains the wording variations across translations.
Did Epictetus say 'it's not what happens to you, but how you react to it that matters'?
That tidy English is a modern paraphrase; the recorded original is Enchiridion 5's line about being disturbed by our judgments about things rather than the things themselves. The paraphrase is faithful in spirit, just not his sentence.
Was Epictetus really a slave?
Yes: born enslaved in Hierapolis, owned in Rome by Epaphroditus, and lamed (one ancient account says by his owner). Freed later, he taught philosophy until Domitian expelled the philosophers, then founded his school in Nicopolis. The biography is why his 'what's in our power' teaching carries unusual weight.