Summary: Sophrosyne is a greek concept of excellent character and soundness of mind that is difficult to translate to english. The translation im using uses the word "temperance" which doesnt quite cover all it's meaning. The main participants in this dialogue are Charmides and Critias that discuss with Socrates what temperance can be defined as.

Charmides is a young man famous for his beauty and temperance. Critias is a person we have seen in previous dialogues who has influenced Charmides. These people are important as they later partake in the oligarchy imposed on Athens by Sparta, forming the Thirty Tyrannts. In the dialogue these people are reasonably and virtous but show hints of their authoritarianism. In Apology we learn that Socrates himself was against the oligarchy and would have suffered consequences had it not collapsed.

Starts with medicine analogy where Socrates explains how doctors never cure just one part of the body but restore health to it as a whole. the soul is the source of health and disease. Spiritual corruption brings bodily unhealth. In the Protagoras dialogue the conclusion seemed to be that temperance was ultimately knowledge like the other virtues, could it be a reference to this?

Throughout the dialogue they debate different possible anwers as to what temperance can be. First Charmides suggests that temperance ins a form of quieteness. Quietness also has a connotation of slowness in Greek. But this definition is disqualified, Socrates brings up examples of things we deem virtous that are not slow or quiet such as writing fast or a body being quick. Next Charmides suggests that it's modesty, as people are ashamed of not being temperate. But this is disqualified because Homer does not deem it suitable for all people? I do not quite understand the reasoning.

Finally, Critias suggests that temperance is minding one's own business. But good people can also do works for others. Such as doctors or craftsmen that do good works for others. Critias makes a distinction between doing and making, where making can never be bad, citing Hesiod. So a temperate person does good for himself and for others. But how does he know when he does good and when he does bad? If a doctor does not know when he does good for another, wouldn't that mean he is ignorant of his own temperance? But temperance ought to include knowing oneself. Is temperance then a science of sciences? The temperate man then knows what he knows and what he does not, in order to always do take the correct decision. They reach the conclusion that this is not temperance, but in fact the science of good and evil instead. Like with the Protagoras dialogue, virtue is always knowledge.

It's impossible to know what you do not know.

At the end Critias commands Charmides to learn from Socrates, and Charmides says that he will follow his command and that Socrates has no choice and the matter and should not oppose him. This can be seen as a nod to the fate of Critias and Charmides, that while they are virtous in the dialogue they will become tyrrants.

Observations:

The dialogue starts out with Socrates saying he will pretend to have a charm that can cure Charmides headaches. I am a bit surprised at this deception, from the Gorgias dialogue i would expect lying to be something Socrates would be against.

The dialogue mentions two mythical doctors (shamans?) named Zalmoxis the Thracian and Abaris the Hyperborean.