STRANGER: But whereas some appear to have arrived at the conclusion that
all ignorance is involuntary, and that no one who thinks himself wise is
willing to learn any of those things in which he is conscious of his own
cleverness, and that the admonitory sort of instruction gives much trouble
and does little good--

THEAETETUS: There they are quite right.

STRANGER: Accordingly, they set to work to eradicate the spirit of conceit
in another way.

THEAETETUS: In what way?

STRANGER: They cross-examine a man's words, when he thinks that he is
saying something and is really saying nothing, and easily convict him of
inconsistencies in his opinions; these they then collect by the dialectical
process, and placing them side by side, show that they contradict one
another about the same things, in relation to the same things, and in the
same respect. He, seeing this, is angry with himself, and grows gentle
towards others, and thus is entirely delivered from great prejudices and
harsh notions, in a way which is most amusing to the hearer, and produces
the most lasting good effect on the person who is the subject of the
operation. For as the physician considers that the body will receive no
benefit from taking food until the internal obstacles have been removed, so
the purifier of the soul is conscious that his patient will receive no
benefit from the application of knowledge until he is refuted, and from
refutation learns modesty; he must be purged of his prejudices first and
made to think that he knows only what he knows, and no more.