courage and patience and intelligence and modesty is verified in the course
of the dialogue. His courage is shown by his behaviour in the battle, and
his other qualities shine forth as the argument proceeds. Socrates takes
an evident delight in 'the wise Theaetetus,' who has more in him than 'many
bearded men'; he is quite inspired by his answers. At first the youth is
lost in wonder, and is almost too modest to speak, but, encouraged by
Socrates, he rises to the occasion, and grows full of interest and
enthusiasm about the great question. Like a youth, he has not finally made
up his mind, and is very ready to follow the lead of Socrates, and to enter
into each successive phase of the discussion which turns up. His great
dialectical talent is shown in his power of drawing distinctions, and of
foreseeing the consequences of his own answers. The enquiry about the
nature of knowledge is not new to him; long ago he has felt the 'pang of
philosophy,' and has experienced the youthful intoxication which is
depicted in the Philebus. But he has hitherto been unable to make the
transition from mathematics to metaphysics. He can form a general
conception of square and oblong numbers, but he is unable to attain a
similar expression of knowledge in the abstract. Yet at length he begins
to recognize that there are universal conceptions of being, likeness,
sameness, number, which the mind contemplates in herself, and with the help
of Socrates is conducted from a theory of sense to a theory of ideas.

There is no reason to doubt that Theaetetus was a real person, whose name
survived in the next generation. But neither can any importance be
attached to the notices of him in Suidas and Proclus, which are probably
based on the mention of him in Plato. According to a confused statement in
Suidas, who mentions him twice over, first, as a pupil of Socrates, and
then of Plato, he is said to have written the first work on the Five
Solids. But no early authority cites the work, the invention of which may
have been easily suggested by the division of roots, which Plato attributes