admit be explanation.
Soc. Then, my friend, there is such a thing as right opinion
united with definition or explanation, which does not as yet attain to
the exactness of knowledge.
Theaet. It would seem so.
Soc. And what we fancied to be a perfect definition of knowledge
is a dream only. But perhaps we had better not say so as yet, for were
there not three explanations of knowledge, one of which must, as we
said, be adopted by him who maintains knowledge to be true opinion
combined with rational explanation? And very likely there may be found
some one who will not prefer this but the third.
Theaet. You are quite right; there is still one remaining. The first
was the image or expression of the mind in speech; the second, which
has just been mentioned, is a way of reaching the whole by an
enumeration of the elements. But what is; the third definition?
Soc. There is, further, the popular notion of telling the mark or
sign of difference which distinguishes the thing in question from
Theaet. Can you give me any example of such a definition?
Soc. As, for example, in the case of the sun, I think that you would
be contented with the statement that the sun is, the brightest of
the heavenly bodies which revolve about the earth.
Soc. Understand why:-the reason is, as I was just now saying, that
if you get at the difference and distinguishing characteristic of each
thing, then, as many persons affirm, you will get at the definition or
explanation of it; but while you lay hold only of the common and not
of the characteristic notion, you will only have the definition of
those things to which this common quality belongs.
Theaet. I understand you, and your account of definition is in my
Soc. But he, who having right opinion about anything, can find out
the difference which distinguishes it from other things will know that
of which before he had only an opinion.
Theaet. Yes; that is what we are maintaining.
Soc. Nevertheless, Theaetetus, on a nearer view, I find myself quite
disappointed; the picture, which at a distance was not so bad, has now
become altogether unintelligible.
Theaet. What do you mean?
Soc. I will endeavour to explain: I will suppose myself to have true
opinion of you, and if to this I add your definition, then I have
knowledge, but if not, opinion only.
Soc. The definition was assumed to be the interpretation of your
Soc. But when I had only opinion, I had no conception of your
Theaet. I suppose not.
Soc. Then I must have conceived of some general or common nature
which no more belonged to you than to another.
Soc. Tell me, now-How in that case could I have formed a judgment of
you any more than of any one else? Suppose that I imagine Theaetetus
to be a man who has nose, eyes, and mouth, and every other member
complete; how would that enable me to distinguish Theaetetus from
Theodorus, or from some outer barbarian?
Theaet. How could it?
Soc. Or if I had further conceived of you, not only as having nose
and eyes, but as having a snub nose and prominent eyes, should I
have any more notion of you than of myself and others who resemble me?
Theaet. Certainly not.
Soc. Surely I can have no conception of Theaetetus until your