Bookcases are almost as old as books. Archaeological remains from earliest times suggest that clay and stone tablets were kept in some arranged order by their authors or collectors. The cylindrical shape of papyrus rolls made them easy to store on shelves. But the inconvenience of reading them--some were more than 100 feet long--led the Romans in the 1st Century to develop the square-shaped manuscript volume, or codex. The codex, with its folded sheets, stitching and binding, was the progenitor of the modern book.