When I start on a book, I have been thinking about it and making occasional notes for some time—20 years in the case of Imperial Earth, and 10 years in the case of the novel I’m presently working on. So I have lots of theme, locale, subjects and technical ideas. It’s amazing how the subconscious self works on these things. I don’t worry about long periods of not doing anything. I know my subconscious is busy.
~Arthur C. Clarke