The Theaetetus is one of the narrated dialogues of Plato, and is
the only one which is supposed to have been written down. In a short
introductory scene, Euclides and Terpsion are described as meeting
before the door of Euclides' house in Megara. This may have been a
spot familiar to Plato (for Megara was within a walk of Athens), but no
importance can be attached to the accidental introduction of the founder
of the Megarian philosophy. The real intention of the preface is to
create an interest about the person of Theaetetus, who has just been
carried up from the army at Corinth in a dying state. The expectation
of his death recalls the promise of his youth, and especially the famous
conversation which Socrates had with him when he was quite young, a few
days before his own trial and death, as we are once more reminded at the
end of the dialogue. Yet we may observe that Plato has himself forgotten
this, when he represents Euclides as from time to time coming to Athens
and correcting the copy from Socrates' own mouth. The narrative, having
introduced Theaetetus, and having guaranteed the authenticity of the
dialogue (compare Symposium, Phaedo, Parmenides), is then dropped. No
further use is made of the device. As Plato himself remarks, who in this
as in some other minute points is imitated by Cicero (De Amicitia), the
interlocutory words are omitted.
Theaetetus, the hero of the battle of Corinth and of the dialogue, is
a disciple of Theodorus, the great geometrician, whose science is thus
indicated to be the propaedeutic to philosophy. An interest has been
already excited about him by his approaching death, and now he is
introduced to us anew by the praises of his master Theodorus. He is a
youthful Socrates, and exhibits the same contrast of the fair soul and
the ungainly face and frame, the Silenus mask and the god within, which
are described in the Symposium. The picture which Theodorus gives of
his 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