Pope Honorius III (1216-1227) wrote a sorcerers manual, or grimiore. In his book, one could learn how to summon demons, keep people out of purgatory, and find out the secrets of heaven.

Pope Leo III ( a contemporary of Charlemagne, circa 800 AD) wrote a spell and charm book, his Enchiridion.

This information was radically different from what the Church officially taught the people.