Introduction

How a work begins – its title, first words, and opening passages – are often taken to be particularly clear indications of an author's intent. The material an author places at the beginning occurs before a plot or an argument exerts constraints. It is reasonable to believe, therefore, that with this greater latitude the author speaks more directly to us, in a manner more reflective of his or her choice. Because of his authorial anonymity such signs are especially valuable to Plato's readers. In these choices the veil of anonymity is for a moment less opaque, affording a glimpse of Plato's authorial hand.

A particular feature of the Theaetetus reinforces this need to fix our attention on the dialogue's opening passages. Throughout the dialogue Socrates insists that Theaetetus must reexamine the beginning of the argument in recognition of the extent to which the starting point of reflection shapes all that follows. As active readers of the dialogue we appropriately apply Socrates’ advice to the dialogue in which it occurs.

Heeding this advice, we must pay careful attention to the dialogue's Prologue. Such care is not misplaced. For the remarkable Prologue with which Plato begins the Theaetetus does shape in discernible ways the subsequent conversation between Socrates and the mathematicians.

Plato uses the device of a prologue in other dialogues, but the Theaetetus' Prologue is distinctive in several respects. The scholarly reaction to it helps us appreciate its unusual character.