Did you know that over 12 million copies of Harry Potter were pre-ordered? … And that's just in the United States. The British Parcel Service (or whatever they call themselves) states that they have 600,000 copies set for Saturday delivery and that’s not counting the copies in stores there. Or in stores around Europe, China, Taiwan and the rest of the world!
Talk about the power of a book.
P.S. Now would be a particularly bad time to start arguing that books are in decline.