Encouragement for Disgruntled Republic-Readers

From my dear Humanities professor, Ralph, part of a very long en masse e-mail to his crop of reluctant freshman. Here, he attempts to explain Plato's approach to knowledge:

"One way to think about what Plato’s up to is to remind yourself of the Pre-Socratics. Remember how they were grappling with the problem of what truly exists, and how do we know what we know? One of the notions lurking back there is that whatever we can have knowledge of must be unchanging. After all, it seems kind of straightforward: I can know this caterpillar -- it's an inch long; it's green; it's got a bunch of legs; etc. And I say, "This is a caterpillar." (I don't say, "This is a dog," or whatever.) But then it turns into a butterfly. So I think OK, I know this butterfly -- it's got yellow wings with black spots and whatnot. And I'm willing to say, "This is a butterfly." (I don't say, "This is a caterpillar.")

But how can I know or even talk coherently about a thing that is coming-to-be? I mean, is it a caterpillar or a butterfly? And don't tell me, well, it's this other thing in between when it's changing, because all you've done then is create a third existing thing, not a thing-coming-to-be. (You've created a butterpillar, maybe.) At what point is it no longer a caterpillar, and at what point is it a butterfly? (Or, at what point is it no longer a caterpillar, and is now a butterpillar? At what point is it no longer a butterpillar, and is now a butterfly? And so on, ad nauseam.) When I say, "This is an X," am I not talking about an X that actually exists, as opposed as coming-to-be? Otherwise, I wouldn't be able to say, "This IS an X." In fact, I say, "This is NOT an X." (You try to get around this by saying, "It WILL be an X." But isn't that just another way of saying it IS NOT an X?)"


Well. The rest of the e-mail was a little more encouraging.
I still don't want to read Plato though, despite Ralph's cunning use of 'butterpillar'.