Every year or so I get the immense privilege of hanging out with Dr. Al Geier, mentor of Dr. John Mark Reynolds, student of Leo Strauss, and the nearest thing to Socrates I've seen yet.
Theaetetus is as psychological as it is philosophical. The psyche, or soul is, after all, that with which we learn and know. It begins in usual Platonic fashion--two individuals are having a conversation about Theaetetus, a prominent Athenian citizen who is returning from battle due to injuries and dysentery. As the individuals talk, they marvel both at Theaetetus' greatness and Socrates' own amazement at Theaetetus. He is sterotypically "full of potential," possibly limited only by an apparent bodily weakness. Socrates uncharacteristically fortells widespread renown for the young man, renown that he may have won in battle.
The central question of the prologue is what the present situation has to do with the past events. The dialogue between Socrates and Theaetetus happened years ago (which immediately brings up epistemological questions). Has Theaetetus changed at all as a result of his time with Socrates? Wounded and dying, yet still determined to go home, he outpaces his healthy companions on the road, but is that a part of his nature or his training with Socrates?
The relationship between a person's nature and his success is difficult, especially in a modern scientific society that eschews any talk of natures that are other than trees and birds and other earthly things.