"I could not sleep when I got on such a hunt for an idea until I had caught it; ...This was a kind of passion with me, and it has stuck by me; for I am never easy now, when I am handling a thought, till I have bounded it north, and bounded it south, and bounded it east, and bounded it west."

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Smaug certainly looked asleep, almost dead and dark, with scarcely a snore more than a whiff of unseen steam, when Bilbo peeped once more from the entrance. He was just about to step out onto the floor when he caught a sudden thin ray of red from under the drooping lid of Smaug's left eye. He was only pretending to sleep! He was watching the tunnel entrance!

— J. R. R. Tolkien