Folk & Demonological · Latin · c. 1499; printed 1606

Johannes Trithemius, abbot of Sponheim

Three books that present themselves as a method for sending messages over distance through spirits, and are the source the Ars Theurgia Goetia takes its thirty-one aerial spirits and their four emperors from. What makes it worth holding is that the presentation is a cover: the long lists of spirit names and the invocations around them in Books I and II encode an ordinary cipher, which was demonstrated within a few years of printing, and Book III held out until 1996 before being shown to be cryptographic too. It was placed on the Index in 1609 regardless, and the grimoire tradition went on borrowing the spirits as spirits. A book read as demonology for four centuries that its own author wrote as cryptography is the cleanest case this corpus has of a text's reception parting company with its contents.