Probably the best-known example of cybertext in antiquity is the Chinese text of oracular wisdom, the I Ching (Wilhelm 1989). Also known as the Book of Changes, the existing text is from around the time of the Western Chou dynasty (1122-770 b.c.) and was written by several authors. The I Ching system also inspired G.W. von Leibniz, who developed the binary mathematics used by today's digital computers (Eber 1979). The I Ching is made up of sixty-four symbols, or hexagrams, which are the binary combinations of six whole or broken ("changing") lines (64=2⁶). A hexagram (such as no. 49, Ko/Revolution) contains a main text and six small ones, one for each line. By manipulating three coins or forty-nine yarrow stalks according to a randomizing principle, the texts of two hexagrams are combined, producing one out of 4,096 possible texts. This contains the answer to a question the user has written down in advance (e.g. "How much rice should I plant this year?").