clearly described, and
the processes of induction and deduction are constantly employed in the
dialogues of Plato. The 'slippery' nature of comparison, the danger of
putting words in the place of things, the fallacy of arguing 'a dicto
secundum,' and in a circle, are frequently indicated by him. To all
these processes of truth and error, Aristotle, in the next generation,
gave distinctness; he brought them together in a separate science. But
he is not to be regarded as the original inventor of any of the great
logical forms, with the exception of the syllogism.

There is little worthy of remark in the characters of the Sophist. The
most noticeable point is the final retirement of Socrates from the field
of argument, and the substitution for him of an Eleatic stranger, who
is described as a pupil of Parmenides and Zeno, and is supposed to have
descended from a higher world in order to convict the Socratic circle of
error. As in the Timaeus, Plato seems to intimate by the withdrawal of
Socrates that he is passing beyond the limits of his teaching; and in
the Sophist and Statesman, as well as in the Parmenides, he probably
means to imply that he is making a closer approach to the schools of
Elea and Megara. He had much in common with them, but he must first
submit their ideas to criticism and revision. He had once thought as
he says, speaking by the mouth of the Eleatic, that he understood their
doctrine of Not-being; but now he does not even comprehend the nature
of Being. The friends of ideas (Soph.) are alluded to by him as distant
acquaintances, whom he criticizes ab extra; we do not recognize at
first sight that he is criticizing himself. The character of the Eleatic
stranger is colourless; he is to a certain extent the reflection of his
father and master, Parmenides, who is the protagonist in the dialogue
which is called by his name. Theaetetus himself is not distinguished
by the remarkable traits which are attributed to him in the preceding
dialogue. He is no longer under the spell of Socrates, or subject to the
operation of his midwifery, though the fiction of question and answer is
still maintained, and the necessity of taking Theaetetus along with him
is several times insisted upon by his partner in the discussion. There
is a reminiscence of the old Theaetetus in his remark that he will not
tire of the argument, and in his conviction, which the Eleatic thinks
likely to be permanent, that the course of events is go