Knowledge of oneself is not easy to attain and Plato was aware of this. In this chapter, we aim to show that he suspected then, like psychologists know now, that one’s introspective capacity to attain knowledge of oneself is very much restricted and that we must rely on the other as a source of such knowledge. We further argue that, for Plato, this knowledge is not easily achieved given not only the shortcomings of the first-person perspective but also the limitations of the third-person one. The third person point of view, however, which in the Platonic model of truth-seeking is given through dialogue, favours self-knowledge.