‘What were you doing?’
‘Why, sitting and thinking. I do a lot of that nowadays, and this is the best place to do it in, as a rule. Wake up, indeed!’ he said, cocking an eye at Elrond. There was a bright twinkle in it and no sign of sleepiness that Frodo could see. ‘Wake up! I was not asleep, Master Elrond. If you want to know, you have all come out from your feast too soon, and you have disturbed me - in the middle of making up a song. I was stuck over a line or two, and was thinking about them; but now I don’t suppose I shall ever get them right.

Book 2, Chapter 1