For I would almost say that self-knowledge is the very essence of temperance, and in this I agree with him who dedicated the inscription "Know thyself!" at Delphi.

Critias's suggestion here (164d) marks the beginning of the central discussion of the Charmides: how we can conceive of self-knowledge as the basis for a beneficial temperance (sophrosyne). Starting with the Delphic command known to all Greeks (a command that Critias understands as a sort of divine "greeting"), the dialogue will develop a much more complex philosophical notion of self-knowledge (see "Self-knowledge" in the Terms section). Plato uses Socratic dialogue (the elenchus) to completely re-frame what most Greeks took to be given knowledge. This process entails a piece of received wisdom being debunked altogether by Socrates. The discussion of "Know thyself," however, is a much more intricate and profound example; it does not seek to show the falsehood of the statement, but to understand it in rational terms, to make ancient wisdom into a new kind of very precise, very demanding knowledge.