Magik systems, initiatory cults, thelema, kabbalah and every other esoteric system.
They are crap. Why are they crap? Due to the nature of the mind, there is an inherent operational system with concepts and mechanisms to it, which is shared by all. But that system is inherently too complex for language, and it is simplified down. Like you have assembler -> C++ -> Phython (and it will only get more similar as we develop A.I programming itself), etc... simplifications written with simplification written with simplifications, until we reach our verbal language and how we talk about these things. Those magic systems try to access that inherent operational system, but they are only "emulations" of it, that affect only the people running those emulators, and no matter how accurate they portray the inherent system, it is still a bubble, and it even keeps them from ever exploring the real system. Even literal programming languages, math, chemistry, geometry and such are better complex languages to think about these things and explore them via metaphor than those magic systems.
For instance, when one of those systems tells you "you have to distill this idea", it is borrowing from Alchemical language. But reading those guides, you will never "comprehend" the abstract concept of distillation. Only via practice of or observation of chemistry you learn exactly what is a distillation, and can use that abstract concept on other things.
