James Richardson:

Writing a book is like doing a huge jigsaw puzzle, unendurably slow at first, almost self-propelled at the end.

Actually, it’s more like doing a puzzle from a box in which several puzzles have been mixed. Starting out, you can’t tell whether a piece belongs to the puzzle at hand, or one you’ve already done, or will do in ten years, or will never do.

(via Alan Jacobs)