In popular culture, the magician invoking dark forces is almost always depicted as a wild, chaotic rebel—an outcast who breaks every divine and human law to strike a desperate pact in blood. Historical grimoires, however, present a radically different reality.

In popular culture, the dark magician is almost always depicted as a wild, chaotic rebel—an outcast who breaks every societal law to strike a desperate bargain with forces of darkness. Historical grimoires, however, tell a radically different story.

In the winter of 1949 a Jesuit priest in St. Louis sat down every night and wrote in a diary. He was recording what happened in a hospital room where he and several other priests were performing the Roman Rite of exorcism on a boy of thirteen from Maryland. He wrote it plainly, without literary flourish, the way a man keeps a log. That diary exists. It sits in an archive, and for most of the last seventy-five years the Society of Jesus has declined to let anyone see it.

Hungarian keeps the creature's name in its everyday vocabulary, where it presses on the language the way it once pressed on sleepers: lidércnyomás — "lidérc-pressing" — is simply the modern Hungarian word for nightmare, the standard term any Budapest office worker uses for a bad dream or a crushing worry. Few of them pause to hear what the word remembers: that the nightmare was once a someone ; that it could be hatched, owned, enriched by, loved by, and ruined by; and that the whole strange career of that someone began — this is the detail no other demon in Europe can match — with an egg carried under a human armpit.

The Physician of Cleves and the Demonological Archive In the late sixteenth century, as the fires of the witch trials burned across Europe, a lone voice of clinical skepticism and Hermetic learning arose from the court of Cleves. Johann Weyer, a Dutch physician who had studied under the legendary occult philosopher Heinrich Cornelius Agrippa, published his monumental work De praestigiis daemonum ("On the Delusions of Demons") in 1563. Appended to later editions of this work was a Latin text that would become one of the most influential documents in the history of Western grimoire culture: the Pseudomonarchia Daemonum , or "The False Monarchy of Demons."