of any doctrine of ideas
except that which derives them from generalization and from reflection
of the mind upon itself. The general character of the Theaetetus is
dialectical, and there are traces of the same Megarian influences which
appear in the Parmenides, and which later writers, in their matter of
fact way, have explained by the residence of Plato at Megara. Socrates
disclaims the character of a professional eristic, and also, with a sort
of ironical admiration, expresses his inability to attain the Megarian
precision in the use of terms. Yet he too employs a similar sophistical
skill in overturning every conceivable theory of knowledge.

The direct indications of a date amount to no more than this: the
conversation is said to have taken place when Theaetetus was a youth,
and shortly before the death of Socrates. At the time of his own death
he is supposed to be a full-grown man. Allowing nine or ten years for
the interval between youth and manhood, the dialogue could not have been
written earlier than 390, when Plato was about thirty-nine years of age.
No more definite date is indicated by the engagement in which Theaetetus
is said to have fallen or to have been wounded, and which may have taken
place any time during the Corinthian war, between the years 390-387.
The later date which has been suggested, 369, when the Athenians and
Lacedaemonians disputed the Isthmus with Epaminondas, would make the
age of Theaetetus at his death forty-five or forty-six. This a little
impairs the beauty of Socrates' remark, that 'he would be a great man if
he lived.'

In this uncertainty about the place of the Theaetetus, it seemed better,
as in the case of the Republic, Timaeus, Critias, to retain the order in
which Plato himself has arranged this and the two companion dialogues.
We cannot exclude the possibility which has been already noticed in
reference to other works of Plato, that the Theaetetus may not have
been all written continuously; or the probability that the Sophist and
Politicus, which differ greatly in style, were only appended after a
long interval of time. The allusion to Parmenides compared with the
Sophist, would probably imply that the dialogue which is called by his
name was already in existence; unless, indeed, we suppose the passage in
which the allusion occurs to have been inserted afterwards. Again,
the Theaetetus may be connected with the Gorgias, either dialogue from
different points of view containi