What does “know thyself” mean?

“Know thyself” — gnothi seauton in Greek — was carved into the forecourt of the Temple of Apollo at Delphi, one of a handful of maxims attributed to the Seven Sages or to the god himself, though it likely started as an older proverb the temple simply preserved. Its original sense wasn’t self-exploration in the modern therapeutic sense; it meant something closer to know your limits — remember you are mortal, not a god, and don’t overreach the place assigned to you. That was standard advice for anyone approaching an oracle: come humbly, don’t presume. Socrates is the figure who bent the phrase toward something new. In Plato’s dialogues he treats self-knowledge not as a warning against pride but as the starting point of virtue itself — you cannot reason well about justice, courage, or the good life if you haven’t first examined what you actually believe and why, including where your own certainty is unearned. His claim that “the unexamined life is not worth living” (Plato, Apology 38a) is essentially gnothi seauton turned into a method: relentless self-questioning as the precondition for wisdom. So the maxim carries two layers later thinkers kept returning to — the older, humbling sense of knowing your place, and the Socratic sense of knowing your own mind well enough to actually live by reason instead of unexamined habit.