Book cipher

Where it comes from

Both sides own the same book, and each word becomes its place in it: page, line, word. In 1779 and 1780 Benedict Arnold's secret letters to the British officer John André were strings of numbers pointing into a copy of Blackstone's Commentaries that both men had. Without the book the numbers mean nothing.

A message worth knowing: We hold these truths. The second Beale cipher, printed in an 1885 pamphlet, is a list of numbers. Number the words of the Declaration of Independence, take each one's first letter, and it reads as a story of buried treasure. Nobody has ever found the treasure.