The study of numbers, and their use in divination, revelation, or prediction. The I Ching is based upon the trigrams, or Ba Gua, as divinations based upon astrology and numerology. Trigrams that represent "variations", instead of divinations can make the Tai Chi, and the Sethian Monadology a measurement instrument of enlightenment. (See "The History of Chinese Philosophy", Vol. 2., by Fun Yu-Lan, Princeton, 1953.)