The abyss, Daath, is a state of primordial entanglement. Daath is the chaos upon which all concept formation is brewed; it is also the infinite process of differentiation from which our mental and psychophysical realities are differentiated. This profound idea is the myth of Tiamat, or Tammuz, the deep, the kthulu of H. P. Lovecraft's stories, the id of Freud, the collective unconscious of Jung, the primal substance of the alchemists, the akasha of the Vedas, the Duat of the Egyptians, [Daath to the Qabalists], and the underworld of the Greeks. Daath is the realm of chaos. It is mysterious, invisible, and secretive. It is considered the realm of occult knowledge.
(Pages 27-30) from Modern Alchemy and Occult Psychology, by D. Lawrence Meredith.