About C. S. Lewis:
I once asked how he managed to write with such ease, and I think his answer tells us more about his writing than anything else he said. He told me that the thing he loved most about writing was that it did two things at once. This he illustrated by saying: "I don't know what I mean till I see what I've said."
The Collected Letters of C.S. Lewis, Volume 3: Narnia, Cambridge, and Joy, 1950 - 1963. 2007. p. xvi.