This chapter has two aims. In section I, I examine the aporia in the Charmides about a certain kind of knowledge (for short, reflexive knowledge): the knowledge of what one knows, that one knows it, and of what one does not know, that one does not know it. The aporia (stated, and referred to as an aporia, at 167B), is whether or not, first, it is possible that there should be such a knowledge as this, and, second, if this is possible, the possession of it would be of any benefit. I concentrate on the following questions. First, what is supposed to be the source of this aporia? And, second, what is supposed to be its positive upshot, especially in view of the fact that this dialogue ends not with a solution to it but on the contrary with a declaration of defeat in the face of it?

In section II, I examine Plato's account of the idea of the good in the Sun-analogy of the Republic. I begin by considering certain central features of this account in its own right, and argue that the idea of the good is characterised as the joint cause of precisely two kinds of thing: on the one hand, the being, truth and knowability of the things that are, are true and are knowable; on the other hand, the ability of the rational soul to know these things.