kinds: it is partly concerned with food for the use of the body, and
partly with the food of the soul which is bartered and received in exchange
for money.

THEAETETUS: What do you mean?

STRANGER: You want to know what is the meaning of food for the soul; the
other kind you surely understand.

THEAETETUS: Yes.

STRANGER: Take music in general and painting and marionette playing and
many other things, which are purchased in one city, and carried away and
sold in another--wares of the soul which are hawked about either for the
sake of instruction or amusement;--may not he who takes them about and
sells them be quite as truly called a merchant as he who sells meats and
drinks?

THEAETETUS: To be sure he may.

STRANGER: And would you not call by the same name him who buys up
knowledge and goes about from city to city exchanging his wares for money?

THEAETETUS: Certainly I should.

STRANGER: Of this merchandise of the soul, may not one part be fairly
termed the art of display? And there is another part which is certainly
not less ridiculous, but being a trade in learning must be called by some
name germane to the matter?