[MD] Simultaneous duality

[X Acto]

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." 
 
-Plato
"Sophist"