From Alan Bennett's Baffled at a Bookcase, to Lucy Mangan's Library Rules, famous writers tell us all about how libraries are used and why they're important. Tom Holland writes about libraries in the ancient world, while Seth Godin describes what a library will look like in the future. Lionel Shriver thinks books are the best investment, Hardeep Singh Kohli makes a confession and Julie Myerson remembers how her career began beside the shelves.