SOCRATES: By all means, Theaetetus, in order that I may see the reflection
of myself in your face, for Theodorus says that we are alike; and yet if
each of us held in his hands a lyre, and he said that they were tuned
alike, should we at once take his word, or should we ask whether he who
said so was or was not a musician?

THEAETETUS: We should ask.

SOCRATES: And if we found that he was, we should take his word; and if
not, not?

THEAETETUS: True.

SOCRATES: And if this supposed likeness of our faces is a matter of any
interest to us, we should enquire whether he who says that we are alike is
a painter or not?

THEAETETUS: Certainly we should.

SOCRATES: And is Theodorus a painter?

THEAETETUS: I never heard that he was.

SOCRATES: Is he a geometrician?

THEAETETUS: Of course he is, Socrates.

SOCRATES: And is he an astronomer and calculator and musician, and in
general an educated man?