A textbook of magic, and the word proves the point of this archive.
Documented
Grammar corrupted into sorcery
French grimoire descends from grammaire, the Latin grammar book. Because magical manuals circulated in Latin among the barely literate, any learned book looked like a sorcerer's book, and the word for one became the word for the other.
Assessment: Documented etymology. The word fossilizes a moment when literacy itself was indistinguishable from magic.
Stories
The book that fights back
The story tradition: grimoires are dangerous objects in themselves, books that must be chained, buried, or read only under protection, and the Grand Grimoire is said to let its reader summon the prime minister of Hell personally.
Assessment: Documented as folklore and as publishing history, since the grimoire trade was real, banned, and profitable. The books had no power; the trade in them had plenty.
Interesting claims
The manuals preserve a suppressed science
The revivalist claim: the grimoires' elaborate rituals encode altered-state techniques, fasting, isolation, repetition, incense, that reliably produce visions, and the spirits were always the operator's own depths.
Assessment: The ritual conditions do match known induction methods for hallucination, which is the interesting overlap. Whether that makes the visions merely psychological or usefully psychological is precisely the argument the archive declines to settle.
Sources and further reading
Davies, Grimoires: A History of Magic Books (2009)
The Grand Grimoire, nineteenth-century French editions
Klaits, Servants of Satan, on the literacy-magic overlap
Worth asking
When did we decide a grammar book was safe and a grimoire was not, and who made that call?