SOCRATES: And what would you say of perceptions, such as sight and hearing, or any other kind of perception? Is there any stopping in the act of seeing and hearing?
THEODORUS: Certainly not, if all things are in motion.
SOCRATES: Then we must not speak of seeing any more than of not-seeing, nor of any other perception more than of any non-perception, if all things partake of every kind of motion?
THEODORUS: Certainly not.
SOCRATES: Yet perception is knowledge: so at least Theaetetus and I were saying.
THEODORUS: Very true.
SOCRATES: Then when we were asked what is knowledge, we no more answered what is knowledge than what is not knowledge?
THEODORUS: I suppose not.
SOCRATES: Here, then, is a fine result: we corrected our first answer in our eagerness to prove that nothing is at rest. But if nothing is at rest, every answer upon whatever subject is equally right: you may say that a thing is or is not thus; or, if you prefer, 'becomes' thus; and if we say 'becomes,' we shall not then hamper them with words expressive of rest.
THEODORUS: Quite true.