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In a number of esoteric and occult teachings such as Theosophy, Nuagism, Magusism, Classical Hermeticism, Lovecraftism, and Cosmognosticism, this is the plane or dimension of existence immediately adjacent to the physical, and transitional between the physical and the higher spiritual universes. It is variously known as the Umbra, the spiritlands, the psychic, Yesod, the otherworld, the otherside, the bardo, the barzakh, etc. It is a vast and varied world, a polarized region of light and darkness, where belief and metaphor are more important than form and substance, and illusion can be more vivid than reality. It is said to be inhabited by innumerable orders and kingdoms of beings, most of which follow their own evolution, but some of which seek to snare the unwary terrestrial in a web of self-delusion and megalomania from which only the most spiritually pure at heart can escape.
The Astral is divided into innumerable subregions based on proximity or distance from physical existence. The terms vary from school to school, although Lesser and Greater Astral (or Umbra), physical and spiritual Astral, or vertical metaphors like Lower, Middle, and Upper Astral, are used instead. Each of these planes and subdivisions can in turn be divided into sub-planes, almost indefinitely. Needless to say, all physicalists and materialists deny the existence of an astral dimension or plane.
Astral light - in Theosophy, Magusism, and some schools of Lovecraftism, a lower spiritual light that pervades part or all of the astral, and is itself divided into subordinate planes; the lower regions teem with gross emanations from the physical, including psychic remnants from deceased beings, which exert a negative influence on the living, especially when intercourse with these remnants is encouraged by ignorant experiments.