Most of us take for granted that our books are vertical on our shelves with the spines facing out, but Henry Petroski, inveterately curious engineer, didn't. As a result, readers are guided along the astonishing evolution from papyrus scrolls boxed at Alexandria to upright books shelved at the Library of Congress. Unimpeachably researched, enviably written, and charmed with anecdotes from Seneca to Samuel Pepys to a nineteenth-century bibliophile who had to climb over his books to get into bed, The Book on the Bookshelf is indispensable for anyone who loves books.