In Kabbalah, the Jewish mystical tradition, Ain, Ain Soph, and Ain Soph Aur are three stages in the process of creation, representing the highest and most abstract levels of divinity:
Meaning "nothing" or "nothingness," Ain represents the unknowable, unthinkable void before creation. It is the absolute absence, beyond all comprehension or description.
Translating to "without end" or "infinite," Ain Soph represents boundlessness. It is the limitless, eternal divine essence, beyond all attributes or definitions.
Meaning "limitless light," Ain Soph Aur is the first manifestation of divine will. It represents the infinite light of creation, the source from which all subsequent emanations and creations emerge.
These concepts form the foundation of Kabbalistic cosmology, describing the process by which the infinite and unknowable divine gradually manifests into the finite, knowable universe we experience.
“The Qabalists expanded this idea of Nothing, and got a second kind of Nothing which they called "Ain Soph"-"Without Limit". (This idea seems not unlike that of Space.) They then decided that in order to interpret this mere absence of any means of definition, it was necessary to postulate the Ain Soph Aur-"Limitless Light". By this they seem to have meant very much what the late Victorian men of science meant, or thought that they meant, by the Luminiferous Ether. (The Space-Time Continuum?) All this is evidently without form and void; these are abstract conditions, not positive ideas. The next step must be the idea of Position. One must formulate this thesis: If there is anything except Nothing, it must exist within this Boundless Light; within this Space; within this inconceivable Nothingness, which cannot exist as Nothing-ness, but has to be conceived of as a Nothingness composed of the annihilation of two imaginary opposites. Thus appears The Point, which has "neither parts nor magnitude, but only position".”
Alistair Crowely, The Book of Thoth, Naples Arrangement