The Know-It-All: One Man's Humble Quest to Become the Smartest Person in the World is a book by Esquire editor A. J. Jacobs, published in 2004.

[1] It recounts his experience of reading the entire Encyclopædia Britannica; all 32 volumes of the 2002 edition, extending to over 33,000 pages with some 44 million words.

By contrast, Joe Queenan in The New York Times Book Review contended that much of which Jacobs reported as remarkable discoveries, e.g. the tale of Heloise and Abelard and the assassination of Marat by a woman, were already common knowledge among educated people.

After reading all of its 18 volumes, the Shah extended his royal title to include "Most Formidable Lord and Master of the Encyclopædia Britannica".

[5] Roughly a century later, Amos Urban Shirk, an American businessman, read the entire 23-volume 1911 Encyclopædia Britannica over a period of four years.