Where grimoires came from
The medieval grimoire tradition is a scholarly one. Its texts are in Latin, they assume knowledge of astrology and Christian liturgy, and they circulated among clerics and university men who were among the very few people able to read them.
Works such as the Picatrix reached Europe through Arabic transmission and Iberian translation, carrying Hellenistic and Persian material with them. The Key of Solomon, the most influential of the later grimoires, survives in dozens of manuscript variants none of which is meaningfully original.
Cheap print changed the audience. By the eighteenth century, condensed and mangled grimoire material was circulating in chapbooks at a price a labourer could meet, which is how ceremonial procedure ended up in the notebooks of village practitioners.
Nineteenth-century occult revivalists then edited, translated and published these texts for a mass readership, and it is those editions, not the manuscripts, that most modern practice descends from.