The reason Milton wrote in fetters when he wrote of Angels and God, and at liberty when of Devils and Hell, is because he was a true poet and of the Devil’s party without knowing it.
– William Blake
I’ve always loved this quotation of Blake’s – it’s from The Marriage of Heaven and Hell, which you should really read. And if you’ve read Paradise Lost, you’ll know that this nails it on the head. The quotation (and the book it comes from) is also rich with meaning about art in general, but what’s really amazing is how Blake wrote the best evaluation of Milton’s magnus opus that I’ve ever read in just 36 words. Whole libraries have been written about Paradise Lost, but Blake did more in one sentence than a thousand academics in their whole lives.
Now that is genius.