"Just remember, you must know everything well before you can know what to discard. You must cover pages with material you will not finally put into the book. That doesn't mean you don't use it. It is still there, must be there, an invisible foundation which gives authority to the story. The planning done on setting is never wasted."

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And therefore education at the University mostly worked by the age-old method of putting a lot of young people in the vicinity of a lot of books and hoping that something would pass from one to the other, while the actual young people put themselves in the vicinity of inns and taverns for exactly the same reason.

— Terry Pratchett