‘How We Know’

To the Editors:

Two corrections to the review of The Information by James Gleick [NYR, March 10]. First, the British Enigma project, which deciphered German military codes in World War II, started with crucial help from Polish cryptologists. Before the war began in 1939, the Poles captured a German Enigma machine and gave copies of it to Britain and France. To have the machine was an essential first step toward deciphering the codes. Second, the Borges “Library of Babel” was not infinite. The number of books was finite but too large to be counted. I thank two vigilant readers for these corrections.

Freeman Dyson
Princeton, New Jersey