every other colour, arises out of the eye meeting the appropriate
motion, and that what we call a colour is in each case neither the
active nor the passive element, but something which passes between
them, and is peculiar to each percipient; are you quite certain that
the several colours appear to a dog or to any animal whatever as
they appear to you?

  Theaet. Far from it.

  Soc. Or that anything appears the same to you as to another man? Are
you so profoundly convinced of this? Rather would it not be true
that it never appears exactly the same to you, because you are never
exactly the same?

  Theaet. The latter.

  Soc. And if that with which I compare myself in size, or which I
apprehend by touch, were great or white or hot, it could not become
different by mere contact with another unless it actually changed; nor
again, if the comparing or apprehending subject were great or white or
hot, could this, when unchanged from within become changed by any
approximation or affection of any other thing. The fact is that in our
ordinary way of speaking we allow ourselves to be driven into most
ridiculous and wonderful contradictions, as Protagoras and all who
take his line of argument would remark.

  Theaet. How? and of what sort do you mean?

  Soc. A little instance will sufficiently explain my meaning: Here
are six dice, which are more by a half when compared with four, and
fewer by a half than twelve-they are more and also fewer. How can
you or any one maintain the contrary?

  Theaet. Very true.

  Soc. Well, then, suppose that Protagoras or some one asks whether
anything can become greater or more if not by increasing, how would
you answer him, Theaetetus?

  Theaet. I should say "No," Socrates, if I were to speak my mind in
reference to this last question, and if I were not afraid of
contradicting my former answer.

  Soc. Capital excellent! spoken like an oracle, my boy! And if you
reply "Yes," there will be a case for Euripides; for our tongue will
be unconvinced, but not our mind.

  Theaet. Very true.

  Soc. The thoroughbred Sophists, who know all that can be known about