-Knowledge is of two kinds, - said Samuel Johnson in 1775. -We know a subject ourselves, or we know where we can find information upon it.- Today we think of Wikipedia as the source of all information, the ultimate reference. Yet it is just the latest in a long line of aggregated knowledge--reference works that have shaped the way we've seen the world for centuries.

You Could Look It Up chronicles the captivating stories behind these great works and their contents, and the way they have influenced each other. From The Code of Hammurabi, the earliest known...