> Can you, metaphysically, define nothing? I ask because I wager you can't,

Are you saying that you can't define "absence"?

But asking me is silly and pointless: I'm no philosopher. And even if philosophers have trouble, that doesn't mean there's no merit to the concept: it just means its difficult.

> and I am highly suspect that metaphysics has philosophical value.

I'm pretty sure you meant the exact opposite of what you actually said, and I strongly suspect you're wrong.