Manuals are often seen as mundane, typical, or otherwise boring. We have manuals for our cars and our microwaves and our assembly-required furniture. But, there was a time when there were manuals for black magic. One of them was called The Clavis Inferni (the Key of Hell) written in the late 18th century. It’s full title is lavis Inferni sive magia alba et nigra approbata Metatrona, which translated into English is: "The Key of Hell with white and black magic proven [or approved] by Metatron."
The book itself is written in several languages, including Latin, Hebrew, and even a cipher-based alphabet. It is believed to be the Black Book, a textbook used of the Black School of Wittenburg (an alleged German magic school). We also don’t know who the author is, as it is labeled as ‘Cyprianus’, however, Cyprianus is a common apocrypha author for magical texts, particularly black magic texts. The mention of Metatrona is a reference to an angel Metatron (referenced in Christian, Jewish, Islamic, and Kabbalistic texts). Metatron may sound familiar to Supernatural fans but this angel is important to magical texts because he is the angel of the veil, celestial scribe, and the highest ranking angel, so it makes sense a manual of magic would be run by him.
The book itself is filled with detailed illustrations, sigils, invocations, directions, and supernatural themes. And, as the subtitle suggests, strong themes of Kabbalah and religion run through it. Several important occult figures also get shout outs in the released pages, including Paymon who is depicted as “King of the West.” Paymon (or Paimon) for those who have seen Hereditary may ring a bell. Paimon was named in the Lesser Key of Solomon (also known as the Ars Goetia), another grimoire complied earlier in the 17th-century. Paimon is a King of Hell obedient to Lucifer. He has various powers that attract his followers including reanimating, create visions, knowledge of all events past and present, and knowledge of secret things.
It also includes information and spells on how to banish a demon, written as Fuga Daemonium. So, it seems that while you may summon and interact with demons...you might also want the ability to banish it back to hell when it has served your purposes.
It was released in the public domain but, to date, a full key to read and understand it has not been made public knowledge or otherwise shared. Historian Benjamin Breen, who discovered the text in Wellcome Images, notes “Only the elect, or those with direct knowledge passed down from a magical practitioner, were thought to be worthy of understanding books like this. Contemporary practitioners of “magick” might try to unlock them, and historians might successfully contextualize them, but in a very real way, these books will always be ciphers to us.”
The above image comes from the Wellcome Library and is liscensed under the public domain.