sophist   

Str. That they went on their several ways disdaining to notice
people like ourselves; they did not care whether they took us with
them, or left us behind them.
Theaet. How do you mean?
Str. I mean to say, that when they talk of one, two, or more
elements, which are or have become or are becoming, or again of heat
mingling with cold, assuming in some other part of their works
separations and mixtures,-tell me, Theaetetus, do you understand
what they mean by these expressions? When I was a younger man, I
used to fancy that I understood quite well what was meant by the
term "not-being," which is our present subject of dispute;
and now you
see in what a fix we are about it.
Theaet. I see.
Str. And very likely we have been getting into the same perplexity
about "being," and yet may fancy that when anybody utters
the word, we
understand him quite easily, although we do not know about
not-being. But we may be; equally ignorant of both.
Theaet. I dare say.
Str. And the same may be said of all the terms just mentioned.
Theaet. True.
Str. The consideration of most of them may be deferred; but we had
better now discuss the chief captain and leader of them.
Theaet. Of what are you speaking? You clearly think that we must
first investigate what people mean by the word "being."
Str. You follow close at heels, Theaetetus. For the right method,
I conceive, will be to call into our presence the dualistic
philosophers and to interrogate them. "Come," we will say, "Ye, who
affirm that hot and cold or any other two principles are the
universe,
what is this term which you apply to both of them, and what do you
mean when you say that both and each of them 'are'? How are we to
understand the word 'are'? Upon your view, are we to suppose that
there is a third principle over and above the other two-three in
all, and not two? For clearly you cannot say that one of the two
principles is being, and yet attribute being equally to both of
them; for, if you did, whichever of the two is identified with
being, will comprehend the other; and so they will be one and not
two."
Theaet. Very true.
Str. But perhaps you mean to give the name of "being" to both of
them together?
Theaet. Quite likely.
Str. "Then, friends," we shall reply to them, "the answer
is plainly
that the two will still be resolved into one."
Theaet. Most true.
Str. "Since then, we are in a difficulty, please to tell
us what you
mean, when you speak of being; for there can be no doubt that you
always from the first understood your own meaning, whereas we once
thought that we understood you, but now we are in a great strait.
Please to begin by explaining this matter to us, and let us no
longer fancy that we understand you, when we entirely misunderstand
you." There will be no impropriety in our demanding an answer to
this question, either of the dualists or of the pluralists?
Theaet. Certainly not.
Str. And what about the assertors of the oneness of the all-must
we not endeavour to ascertain from them what they mean by "being"?
Theaet. By all means.
Str. Then let them answer this question: One, you say, alone is?
"Yes," they will reply.
Theaet. True.