The Grimoire is in many ways a myth- anything advertising itself as a "Grimoir" these days is a guaranteed hoax, in the Middle Ages when books were expensive to make, the language functioned differently, our concept of a "Grimoir" comes from this period of History. Today a grimoir is anything supposed to yeild earthly power- influencing reality or Being Itself falls under the category of "The Supernatural" (eg. Beyond Nature, Beyond things as they happen in themselves, Beyond the Known, Recognizeable, the Self, which can be termed "Beyond the Self," "The Beyond" or "The Beyond Self.") which is accessed on the dimension of Being known to the Buddhists as "PariNirvana," which is often ignored in light of the shocking truth that "Nirvana," or "Freedom from Suffering" means Negation, or Death, and is associated with the recognition of "No-Self," while PariNirvana is associated with "The Self." literally Beyond The No Self.
For this reason my recomendation is to study everything, but especially The Bhagavadgita, the tao De Ching, the Odin Brotherhood (by Mark Mirabello), the Satanic Bible, Thus Spoke Zarathustra, being and time, Being and Nothingness, and Royal attire, a book written by a Karaite Hakhim wherein he attacks Orthodox Judaism and the Talmud- he providesa very simple breakdown of Jewish philosophy, which is often avoidedby Jews as their talmud teaches them never to tell a gentile what the talmud says. The reasons for this are well known to anyone familiar with it- probably why the Rabbis have consistently avoid any fair discussions of the Oral Torah with them by use of a variety of tricks.
On one occasion a Karaite went to a king in a given area to argue the Talmud IN FRONT OF HIM, and when the rabbi camehe used the opportunity to claim that a karaite stole Moses's sandals for some reason, and when the Karaite pointed out that the word karaite originated in the 7thcentury the rabbi proclaimed victory by claiming he admited defeat.
Of course anyone familiar with Jewish history would know that this was by no means an admission- but was in fact the harshest condemnation of the Talmud imagineable- it was a pure hoax, so prior to its becoming mainstream there was no use for the distinction "Karaite."
