STRANGER: I ask whether anybody can understand all things.
THEAETETUS: Happy would mankind be if such a thing were possible!
SOCRATES: But how can any one who is ignorant dispute in a rational manner against him who knows?
THEAETETUS: He cannot.
STRANGER: Then why has the sophistical art such a mysterious power?
THEAETETUS: To what do you refer?
STRANGER: How do the Sophists make young men believe in their supreme and universal wisdom? For if they neither disputed nor were thought to dispute rightly, or being thought to do so were deemed no wiser for their controversial skill, then, to quote your own observation, no one would give them money or be willing to learn their art.
THEAETETUS: They certainly would not.
STRANGER: But they are willing.
THEAETETUS: Yes, they are.