Abstract The purpose of this paper is to re-evaluate the position and role of Plato’s Charmides by analysing its second part. In this section, Critias tries to explain sôphrosunê as a form of knowledge that is self-referential in the sense that it is a type of knowledge of all other forms of knowledge without being knowledge of the objects of those other forms. Plato remains doubtful about the feasibility and usefulness of such a concept, as he believes that all types of knowledge must be about something else, separate from the forms of knowledge themselves. He also thinks that such formal knowledge, if it indeed exists, is of little interest. This paper also aims to demonstrate that the Charmides belongs to a group of dialogues in which Plato discusses other people’s proposals, similar to what happens in the Theaetetus. In the case of the Charmides, this is very likely the project that we will later see developed in Aristotle’s Posterior Analytics.