[250d]
a thing is not in motion, it must surely be at rest; and again, what is not at rest, must surely be in motion. But now we find that being has emerged outside of both these classes. Is that possible, then?
Theaetetus
No, nothing could be more impossible.
Stranger
Then there is this further thing which we ought to remember.
Theaetetus
What is it?
Stranger
That when we were asked to what the appellation of not-being should be applied, we were in the greatest perplexity. Do you remember?
Theaetetus
Of course I do.
Stranger
Well, then, are we now in any less perplexity