tes, who does not know his name, recognizes him as the son of
Euphronius, who was himself a good man and a rich. He is informed by
Theodorus that the youth is named Theaetetus, but the property of his
father has disappeared in the hands of trustees; this does not, however,
prevent him from adding liberality to his other virtues. At the desire
of Socrates he invites Theaetetus to sit by them.

'Yes,' says Socrates, 'that I may see in you, Theaetetus, the image
of my ugly self, as Theodorus declares. Not that his remark is of any
importance; for though he is a philosopher, he is not a painter, and
therefore he is no judge of our faces; but, as he is a man of science,
he may be a judge of our intellects. And if he were to praise the mental
endowments of either of us, in that case the hearer of the eulogy ought
to examine into what he says, and the subject should not refuse to be
examined.' Theaetetus consents, and is caught in a trap (compare the
similar trap which is laid for Theodorus). 'Then, Theaetetus, you will
have to be examined, for Theodorus has been praising you in a style of
which I never heard the like.' 'He was only jesting.' 'Nay, that is not
his way; and I cannot allow you, on that pretence, to retract the assent
which you have already given, or I shall make Theodorus repeat your
praises, and swear to them.' Theaetetus, in reply, professes that he is
willing to be examined, and Socrates begins by asking him what he learns
of Theodorus. He is himself anxious to learn anything of anybody; and
now he has a little question to which he wants Theaetetus or Theodorus
(or whichever of the company would not be 'donkey' to the rest) to find
an answer. Without further preface, but at the same time apologizing
for his eagerness, he asks, 'What is knowledge?' Theodorus is too old
to answer questions, and begs him to interrogate Theaetetus, who has the
advantage of youth.

Theaetetus replies, that knowledge is what he learns of Theodorus,
i.e. geometry and arithmetic; and that there are other kinds of
knowledge--shoemaking, carpentering, and the like. But Socrates rejoins,
that this answer contains too much and also too little. For although
Theaetetus has enumerated several kinds of knowledge, he has not
explained the common nature of them; as if he had been asked, 'What is
clay?' and instead of saying 'Clay is moistened earth,' he had answered,
'There is one clay of image-makers, another of potters, another of
oven-make