"All right," said Hermione, disconcerted. "Say the Cloak existed ... what about the stone, Mr. Lovegood? The thing you call the Resurrection Stone?"

"What of it ?"

"Well, how can that be real?"

"Prove that it is not," said Xenophilius.

Hermione looked outraged.

"But that's - I'm sorry, but that's completely ridiculous! How can I possibly prove it doen't exist? Do you expect me to get hold of - of all the pebbles in the world and test them? I mean, you could claim that anything's real if the only basis for believing in it is that nobody's proved it doesn't exist!"

"Yes, you could," said Xenophilius.