Let us hold our discussion together in our own persons, making trial of the truth and of ourselves.

As Socrates prepares to begin his turn at asking Protagoras questions (348a), he gives a concise statement of what he perceives the purpose of philosophy to be. Philosophical thinking is not merely a search for truth, nor is it only a way of testing the self. Rather, it should unite both these aspects. Discussions can only take place between people, and this simple fact should shape the form those discussions take. In arguing with someone, we should not merely argue with their opinions, but with those opinions as that person embodies them. Using a poem as a medium between the two interlocutors—as Protagoras does—interrupts this confrontation of true personalities.

But there is a harsh irony here, for Plato himself argues through characters in the dialogues. Instead of holding a discussion in his own person, Plato uses masks to represent his opinions. Socrates's belief in the importance of the unvarnished truth immediately spoken by a person appears in a very mediated form, itself spoken in a hypothetical dialogue written down half a century after it is supposed to have taken place.