Most of what we say about books is really about their contents: the rosy nostalgic glow for childhood reading, the lifetime companionship of a much-loved novel. But books are things as well as words, objects in our lives as well as worlds in our heads. And just as we crack their spines, loosen their leaves and write in their margins, so they disrupt and disorder us in turn. All books are, as Stephen King put it, 'a uniquely portable magic'. In this thrilling history, Emma Smith shows us why.