Book excerpt: What exactly is a book? This wildly inventive and thought-provoking volume asks that question of more than 30 of today's top creative visionaries, from Ed Ruscha to Miranda July, John Baldessari to Jonathan Lethem. Each traditional element of a book—from endpapers to footnotes—is assigned to a different artist or writer invited to use the space as a creative playground. The result is a collaborative group art project like no other. A ribbon bookmark by David Shrigley, page numbers by Tauba Auerbach, endnotes by Rick Moody—each contribution surprising and brilliant. This one-of-a-kind book will entrance anyone who appreciates art, literature, and the surprising possibilities that emerge when the two collide.