(codified ca early 14th c.) Claimed to be a part of Torah given to Adam, the Kabbalah (the word means "tradition") is a mystical system that concerns itself with the process of creation. Because of its esoteric, gnostic elitist nature and its emphasis on magic, the conjuring of supernatural forces, numerology, astrology, reincarnation, etc., watered-down Kabbalah has become a trendy, New Age fashion.
True Kabbalah, however, is for initiates and is not supposed to be studied until one is firmly grounded in basic Judaic principles (usually around the age of 40 among the non-Hassidic). Parts of Kabbalah are in print (the Zohar --"Book of Splendor"-- by Moses de Leon, for example), but other parts are a matter of orally transmitted, deeply secret tradition. Kabbalah has played a great role in the development of many diverse movements, including Masonry, Rosicrucianism, Renaissance-era secular and Christian thought, Aleister Crowley's Hermetic Order of the Golden Dawn (and other Hermetic systems), and Mormonism.