SOCRATES: Then now apply his doctrine to perception, my good friend, and first of all to vision; that which you call white colour is not in your eyes, and is not a distinct thing which exists out of them. And you must not assign any place to it: for if it had position it would be, and be at rest, and there would be no process of becoming. THEAETETUS: Then what is colour? SOCRATES: Let us carry the principle which has just been affirmed, that nothing is self-existent, and then we shall see that white, black, and 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? THEAETETUS: Far from it. SOCRATES: 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? THEAETETUS: The latter. SOCRATES: 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. THEAETETUS: How? and of what sort do you mean? SOCRATES: 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? THEAETETUS: Very true. SOCRATES: 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? THEAETETUS: 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. SOCRATES: 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. (In allusion to the well-known line of Euripides, Hippol.: e gloss omomoch e de thren anomotos.) THEAETETUS: Very true.