In Chapter 18, Part IV of Book Four: Magick in Theory and Practice, Aleister Crowley gives a brief summary of his understanding of how divination “works.”
“The theory of any process of divination may be stated in a few simple terms.
1. We postulate the existence of intelligences, either within or without the diviner, of which he is not immediately conscious. (It does not matter to the theory whether the communicating spirit so-called is an objective entity or a concealed portion of the diviner’s mind.) We assume that such intelligences are able to reply correctly — within limits — to the questions asked.
2. We postulate that it is possible to construct a compendium of hieroglyphs sufficiently elastic in meaning to include every possible idea, and that one or more of these may always be taken to represent any idea. We assume that any of these hieroglyphics will be understood by the intelligences with whom we wish to communicate in the same sense as it is by ourselves. We have therefore a sort of language. One may compare it to a “lingua franca” which is perhaps defective in expressing fine shades of meaning, and so is unsuitable for literature, but which yet serves for the conduct of daily affairs in places where many tongues are spoken. Hindustani is an example of this. But better still is the analogy between the conventional signs and symbols employed by mathematicians, who can thus convey their ideas perfectly without speaking a word of each other’s languages.
3. We postulate that the intelligences whom we wish to consult are willing, or may be compelled, to answer us truthfully.”
As explicated in subsequent paragraphs, the key point of this theory (while acknowledging the currently fashionable – and psychologically plausible – assumption that the subtle communication actually taps into the diviner’s or subject’s subconscious awareness of the circumstances of the inquiry) is that there are non-corporeal “intelligences,” specifically astral-plane “spirits,” that are inclined to (or that can through force of Will be bidden to) answer truthfully any questions put to them that are within their designated purview. Elsewhere in the chapter, Crowley cautions that it is inadvisable to overshoot the mark and approach intelligences that are too exalted in stature to stoop to addressing one’s petty mundane concerns. He alludes to the risk of encountering intentional deception or sly trickery (some of which may be maliciously harmful) on the part of elevated spirits that are offended by being importuned in this manner.
I submit that these are not the benign “spirit guides” that so many people assume are personally attached to them and that are vitally interested in their spiritual advancement. These beings – which are sometimes described as daemons and accorded angelic Hebrew names – must be called upon (evoked) when needed and are not constantly looking down upon us with benevolent intent. They are independent entities with their own private objectives, going about their business in the astral realm, and they may at first be reluctant to cooperate (hence the need for coercion and the setting of robust “wards of protection”). Crowley advises becoming friendly with them in a familial way through regular interaction and dialogue such that they are eager to partner with and assist us.
I have to say that I’m partial to the psychological explanation for “how divination works” rather than the purely mystical or magical one. It makes sense to me that the uncharted territory from which we receive messages resides in the personal subconscious and affords us a window on the Collective Unconscious through which knowledge of hidden things can be channeled into our conscious perception. It turns the popular conception of “hunches” or “educated guesses” into something generally more reliable. The human mind holds much as-yet-unrealized potential, and I see no useful purpose in personifying the culmination of its prowess as an autonomous presence exhibiting an uncertain and possibly hostile posture toward the supplicant. So I guess I’ll just sit here and wait for the “lightning bolt from on high” to strike me down for my heresy.