What if you slept? And what if, in your sleep, you dreamed? And what if, in your dream, you went to heaven and there plucked a strange and beautiful flower? And what if, when you awoke, you had the flower in your hand? Ah, what then?
Coleridge isn't simply marveling at the boundary between dream and waking—he's asking whether such a boundary even matters once the evidence becomes tangible. The real power lies in his refusal to dismiss the dream as "mere" fantasy; if the flower exists in your hand, the dream's reality becomes unquestionable, regardless of its origin. When you've genuinely created something beautiful during a sleepless night of writing or problem-solving, only to find it holds up in the morning light, you understand his question perfectly—the source of inspiration becomes irrelevant once the work proves itself in the world.