or may not be a 'gracious aid' to thought; but it cannot be got rid of.
The other figure of the enclosure is also remarkable as affording the first
hint of universal all-pervading ideas,--a notion further carried out in the
Sophist. This is implied in the birds, some in flocks, some solitary,
which fly about anywhere and everywhere. Plato discards both figures, as
not really solving the question which to us appears so simple: 'How do we
make mistakes?' The failure of the enquiry seems to show that we should
return to knowledge, and begin with that; and we may afterwards proceed,
with a better hope of success, to the examination of opinion.

But is true opinion really distinct from knowledge? The difference between
these he seeks to establish by an argument, which to us appears singular
and unsatisfactory. The existence of true opinion is proved by the
rhetoric of the law courts, which cannot give knowledge, but may give true
opinion. The rhetorician cannot put the judge or juror in possession of
all the facts which prove an act of violence, but he may truly persuade
them of the commission of such an act. Here the idea of true opinion seems
to be a right conclusion from imperfect knowledge. But the correctness of
such an opinion will be purely accidental; and is really the effect of one
man, who has the means of knowing, persuading another who has not. Plato
would have done better if he had said that true opinion was a contradiction
in terms.

Assuming the distinction between knowledge and opinion, Theaetetus, in
answer to Socrates, proceeds to define knowledge as true opinion, with
definite or rational explanation. This Socrates identifies with another
and different theory, of those who assert that knowledge first begins with
a proposition.

The elements may be perceived by sense, but they are names, and cannot be