The Greek term sophrosyne, though it denotes perhaps the highest ideal in Greek thought, is impossible to translate fully with any single English word. Sophrosyne, as Hamilton and Cairns point out in the Princeton edition of Plato's dialogues, encompassed two of the most crucial sayings of the oracle at Delphi: both 'Know thyself' and 'Nothing in excess.' The term thus suggests a kind of order or balance that stretches from the innermost reaches of the soul to the surface of the body and on to the way that body moves and what the whole person does. Sophrosyne is a grace and a goodness that comes from self- possession, and it is in this sense that it drives the Charmides's almost obsessive concern with the mechanism by which self-knowledge translates into concrete knowledge and thence into beneficial action.
The elenchus is the primary method of Socratic philosophy. It proceeds by an intensive series of questions and refutations, and aims to lead the interviewee to conclude for himself that he does not know what he thought he knew (a state of uncertainty with regard to the topic at hand). The form of elenchus taken by Socrates in his debate with Charmides is fairly standard, though somewhat skewed in places by Socrates's overwhelming attraction to the young man. Things change when Critias takes over as interlocutor; although he is never set out as a famous wise man or philosopher, he is given far more lines than the usual elenchus allows, and these lines are often philosophically substantive. The elenchus becomes the specific object of dispute at one point in the dialogue, when Critias accuses Socrates of being more concerned with refuting him than with advancing the discussion. Socrates replies that such refutation is precisely what does advance the discussion, and that any refutation of Critias is equally a self-examination on Socrates's part. This exchange is a rare and valuable consideration of the elenchus as a kind of unity, through productive negation, of separate identities in philosophical exchange.
Self-knowledge is second only to temperance in terms of the dialogue's central themes—in fact, temperance is defined as a kind of self-knowledge for much of the discussion, from the moment Critias cites the Delphic oracle's command to "Know thyself." But self-knowledge in the Charmides is a much more complex proposition than simple self-awareness or self-consciousness. Specifically, it is a knowledge both of what one knows and of what one does not know. There are a number of sticky paradoxes here, not the least of which concerns how anyone can know what they do not know (toward the end of the dialogue, Socrates reflects that "nothing can be more irrational"). This issue is generalized in places as a problem of how anything can be defined by its relation to itself; it would seem, if this is the case, that the thing would be both itself and something else. Self-knowledge is also discussed, with these same qualities in mind, as a kind of meta-science, a 'science of science' that knows itself and all other sciences (but not the specific, concrete things that those other sciences know). A second problem arises here: how can self-knowledge ever have an effect on any practical realm of knowledge, if its 'subject matter' is nothing but knowledge itself? Paradoxes like this one ultimately confound the dialogue.