“Where is happiness?” For years this was my driving question. Perhaps it was yours, too.

The question proved a persistent one, not because it was stubborn, but because I was: I insisted on looking in all the wrong places. I looked in so-called accomplishments—law school, publishing, test scores. I looked in others—friends, girlfriends, family. I looked in objects—video games, books, movies. At my lowest points, I looked in the easy lull of alcohol or other ersatz vices. And yet, this thing—“happiness”—never lingered. Every now and then I’d grab hold of it, yet like a hand-caught fish it would quickly squirm away. Because—and here’s a cliché that’s easy to recall yet difficult, so difficult, to live—happiness is not outside. Happiness is inside. Happiness lies in the one thing none of us ever give up: The ability to choose how we respond to any given situation.

For it is not things that trouble us, but our interpretations of those things. We’ve forgotten that this great power of interpretation resides within us, and so we go begging outside ourselves for happiness. But what is external is by nature tenuous; the only lasting happiness comes from declaring one’s independence from things, people, and events. Things do not trouble you. People do not trouble you. Events do not trouble you. Your interpretations of them trouble you.

The slave is Epictetus; the emperor is Marcus Aurelius; the tutor is Seneca. They are thoroughly dead, all of them, and yet — as reflected by hundreds of recent works such as Ryan Holiday’s The Daily Stoic — their knowledge is very much alive. Like Eastern wisdom, this neglected pre-Christian wisdom of the West has much to offer; I would go so far as to say that it offers, at least, an outline to be content under the toughest circumstances.