Lucilius had apparently been traveling — moving from city to city, hoping that a change of scene might settle something restless inside him. Seneca's response in Letter 28 is one of the most direct things he ever wrote. The problem, he tells his friend, is not where you are. It is what you bring with you.
"Do you ask why this fleeing and this change of place does not help you? It is because you take yourself with you."
The letter is usually read as being about anxiety or depression — the futility of trying to outrun your own mind. But there is another layer to it that tends to get overlooked. What else do you take with you, everywhere you go? Your standards. Your criteria for what counts as acceptable behavior, good thinking, worthy effort. Your sense of what "right" looks like. Seneca is pointing at a person who has packed their measure of the world alongside their sandals, and who arrives in every new place already knowing how it will fall short.
This shows up elsewhere in the letters in a subtler form. In Letter 7, Seneca warns against spending too much time with crowds — not because crowds are morally inferior, but because our tendency is to import their worst qualities without noticing, and export our judgments without examining them. And Letter 50 has him observing that we are remarkably quick to see the faults in others that we cannot detect in ourselves: "We censure what we are." The person who is sharpest about other people's stubbornness is usually defending their own. The one most appalled by closed-mindedness is often least aware of the doors they've already locked.
Marcus Aurelius spent years returning to this same problem in his private notebooks — the book we now call the Meditations — and what's striking is how explicitly he treats his own irritation at others as a diagnostic tool pointing back at himself. In Book 9 he writes that when we're disturbed by someone's failure, we should remember that the disturbed person and the failing person share the same nature. We were made for cooperation, not for contempt. And in Book 5 he goes further: the person behaving badly is doing so out of ignorance, not malice, because no one chooses what they believe to be wrong. Getting angry at them is like being angry at someone for being shortsighted. The Meditations — which Marcus never intended to publish; it was a private self-correction — is the record of a powerful man struggling, repeatedly, with the habit of sitting in judgment over everyone around him. He never quite beat it. But he never stopped treating it as a problem to be worked on rather than a faculty to be exercised.
The uncomfortable convergence of Seneca and Marcus here is this: the measuring stick you carry is yours. It came from your particular history, your particular formation, the particular things that were praised and blamed when you were learning how the world worked. Other people are carrying different sticks, calibrated differently, and they are no more wrong to trust theirs than you are to trust yours. What you call failing to meet the standard, they might call following a different one entirely.
The measure is real — you shouldn't abandon it. But there's a difference between knowing what you value and assuming everyone else is deficient for not sharing it. Seneca's line is worth turning over: you take yourself with you. The question is whether you also take, packed right next to the standards, any curiosity about how they were made.