I was reading The Fellowship of the Ring to my son and came across this description of the Hall of Fire in Rivendell, ancient home of the elves.
Frodo found himself walking with Gandalf. ‘This is the Hall of Fire,’ said the wizard. ‘Here you will hear many songs and tales – if you can keep awake. But except on high days it usually stands empty and quiet, and people come here who wish for peace, and thought. There is always a fire here, all the year round, but there is little other light.’
That seems like a good description of the contemplation in which I imagine Tolkien daydreaming his lore to life. It also seems like a great description of meditation: perhaps especially the threat of falling asleep.