A professor in Renaissance Italy leads a double life, teaching law by day and practicing demonology by night. The untold story of a series of cases that shook the Catholic Church and shaped its spiritual battles.

1872: Thomas Allen’s bookstore, London, England

Isidore Liseux, 37, clenched the delicate, fading manuscript written in ancient Latin. The French bibliophile and collector had rummaged through the small bookstore near Regent’s Park in London, on the lookout for hidden gems among rare editions of poetry and theology. He hardly expected to stumble on a mystery.

Though he suspected it could be valuable, it would take time and meticulous effort to uncover the nature of what he had found. Liseux, a former seminary student, would identify the author of the manuscript as Ludovico Maria Sinistrari, a 17th century Franciscan polyglot: a priest, theologian, professor and lawyer. The manuscript, as Liseux would come to realize, had been too controversial to ever be published.

This dangerous work had been copied out by hand and secretly passed around for nearly two centuries, circulating in monasteries before disappearing into legend. Until now. Liseux paid the bookseller sixpence for his prize and exited the shop into the London streets. He had just unwittingly rediscovered the story of a master demonologist assigned to resolve some of the most bizarre mysteries in Catholic Church history, including a chain of cases that became a personal and institutional crisis.

1670: Pavia, Italy

Professor Ludovico Sinistrari, 38, crossed the courtyard through the gleaming morning sunlight on the way to teach classes. He was easy to spot even in a crowd: tall, wide-shouldered, with an inviting demeanor. He could banter and joke with his colleagues and students alike.

The University of Pavia was not merely one of the oldest schools in Italy, but one of the oldest in the world. Sinistrari was one of the few law professors on campus who was also a member of the clergy, serving as a Franciscan priest and theology instructor. Some of his colleagues were dubious—the secular law school stressed its independence from the church—but he earned their respect. As an alumnus of the university, Sinistrari understood the culture and the particular challenges to the region. Years of war and famine had decimated the once large population. Residents remained on edge, manifesting in outbreaks of violence. On campus, a rite of passage called spupillazione involved forced payments from new students to upperclassmen, which could often lead to fights. Some law students were said to carry swords.

Students with ambitions in law flocked to study under Sinistrari. He taught the encyclopedic Roman Digest and Codex, or collection of laws, to his civil students, and the Decretum Gratiani and Liber Sextus, compendiums of church legislation and methods, to his canon students. A skilled orator, Sinistrari would present these foundational texts and more contemporary case examples, while students were responsible for memorizing these lectures. No easy task, but sitting in Sinistrari’s lectures was like watching a performance.

Sinistrari taught law at Pavia in the morning and then theology in the evening at the local Convento di Sante Croce. The contrast felt appropriate; in daylight his life was a worldly one, but in darkness he was informed by ancient, mysterious arts.

His religious training had begun as a teenage friar at the Franciscan Monte Mesma monastery in his hometown of Ameno. The town’s name meant “pleasant,” and the monastery was at the summit of the mountain, from which the resident friars felt like they could see the entire world. Villages and castles were visible from the peak—one could spot Milan in the distance. The majestic Agogna streamed down the mountain into Lake Orta below.

The monastery itself felt remote, all the more so because of its ancient setting. Its library included one of the first editions of Dante’s Inferno, arguably the most convincing cartography of evil in Catholic literature. Above doorways hung traditional Franciscan reminders that had a formative influence on the young friar: Pray for sinners. Offer peace to the sick. Give eternal rest to those who have suffered.

By the age of 16, Sinistrari had the opportunity to witness the most experienced friars convert those mottos into action, as in the case of a woman in town who was reported to be suffering from a demonic possession. It was determined that she needed an exorcism, and not just any kind. The Roman Rite of exorcism, which remains the most familiar today, was codified and put into practice more than 30 years earlier. But the Franciscans had a separate tradition of exorcisms anchored in complex concoctions and “suffumigation,” the practice of burning herbs, plants, and other materials to generate fumes into the environment that they believed disrupted malicious entities.

Jesus Christ was the first exorcist in the Christian tradition, as depicted in multiple episodes in the New Testament and in Franciscian methods. Franciscians, on some level, bridged pre-Christian exorcisms’ use of intermediary objects and Christ’s explicit reliance on the power of God. Sinistrari observed the use of such techniques on the local Ameno woman, as well as in other cases in which the monastery got involved.

Now, with Sinistrari situated in Pavia as a respected professor, word spread about his specialized expertise in arcane spiritual matters, which could be deployed when conventional methods failed. This led to something of a double life. For his fellow law faculty at the University of Pavia, an unusual day might involve a time sensitive request to represent a case at the court. For Sinistrari, on the other hand, a knock on the door after hours could signal a spiritual emergency requiring his urgent intervention.

The typical case would arrive with a confidential message from a worried monk or other member of the clergy. Sinistrari would depart with his Bible and his copy of Girolamo Menghi’s Flagellum Daemonum, which laid out in great detail Franciscan techniques for expelling demons. He would wear the traditional gray Franciscan tunic in the tradition of the order’s founder, Saint Francis of Assisi (in later centuries, the Franciscan order would wear a brown habit). In his black satchel, he carried the tools of his trade, including a glass vessel and a highly curated selection of herbs, seeds and spices such as rue, sweet cane, cubeb seed, cardamon, ginger, brandy, cloves and aristolochia root. To the average Pavian it may have all looked benign, but according to his training these modest materials could help overcome the most powerful invisible adversaries.

Not far from the university where Sinistrari delivered his heady lectures, a woman named Hieronyma was doing her errands around town, including at the bakery. Alongside the bread she was picking up, she was surprised to find a large cake made with butter and paste. She insisted it was not hers, but the baker was adamant he had no one else’s orders that he had prepared.

She decided she may as well enjoy the unexpected treat, so she and her husband shared the cake. The next night, while sleeping, she woke to a sharp whisper: “Was the cake to your taste?” She jolted upright, and saw that her husband was sound asleep. No one else was there. Hieronyma crossed herself and prayed to Jesus and the Virgin Mary.

“Be not afraid,” whispered the shrill voice. “I mean you no harm … I am prepared to do anything to please you.” As Hieronyma reported later, she began to feel gentle, feather-like kisses on her cheeks. They felt as if they came from lips that were physical but unreal, almost gaseous. Disgusted, she shrank back into the bed, but the feeling of being kissed continued while she prayed until the presence abruptly disappeared. This was the start of repeated incidents. She felt terrorized and under constant surveillance; she no longer felt safe.

Hieronyma went to her parish, San Michele Maggiore, where she confided in the priest about her experience. The priest advised her to gather whatever holy relics she could find to guard against the intrusion. Still, the reports of nightly experiences continued: the seductive whispers, the continuous kissing and her horrified rejection.

Exhausted and baffled, Hieronyma agreed to an exorcism. The priest prepared the traditional Roman Rite, but the exorcist was pessimistic because Hieronyma did not appear to be possessed, which would have involved a malicious spirit occupying her body. The case lacked what were considered clear indications of possession by the church, such as strange colorations, speaking in unusual pitches or tongues, showing unusual amounts of strength, making prophecies about the future, and acting violently. The priest performed a blessing on the entire house and warned the demon never to return.

As the priest feared, the exorcism had little impact. In fact, the attempt seemed to intensify the harassment, pleading and wailing during the night.

With all involved desperate for answers, the woman’s situation was brought to Professor Sinistrari’s attention. His theological studies had led to a long study of two specific categories of demons, known as incubi (which were male) and succubi (female). These entities were said to have no interest in possession or taking over and controlling human bodies; instead, they specifically sought carnal experiences with humans.

Demonology—a study of the identities, characteristics, and powers of demons— had a deep and complex tradition in the Catholic faith. Beginning with Bishop Melito of Sardis in the second century, demonology was an important subject for influential early church writers, including Saint Augustine. In 1215, the Fourth Lateran Council, which set theological doctrines, stipulated that “the devil and other demons were created by God naturally good, but they became evil by their own doing,” affirming the theology of demons as fallen. Heinrich Kramer, a 15th century Dominican priest, penned a controversial treatise on witchcraft and demon possession, a work followed by King James VI of Scotland (later king of England), whose 16th century Demonology became foundational to the field. Because demonology dealt with the very nature of evil, it was fraught with the fear of sin. As 13th century priest Albertus Magnus warned, A daemonibus docetur, de daemonibus docet, et ad daemones ducit: “It is taught by the demons, it teaches about the demons, and it leads to the demons.”

Sinistrari would not be surprised that traditional exorcism had not worked in Hieronyma’s case. Demons in this category would stop at nothing—short of consummation—to achieve their desires, as they were driven by a genuine if perverted form of love. The nightly visitation by the entity were either attempts to exhaust Hieronyma into submission or to trigger pity in her. For those who studied scriptural and anecdotal accounts of such demons, these entities were considered unusually malicious and powerful. In demonology, they were distinguished by the fact that they temporarily could assume corporeal form.

Modern skeptics of Sinistrari’s demonology could point to societal anxieties about sexuality and suppression of sexual desires as giving rise to irrational fears of the existence of such carnal demons; true believers could point to these same anxieties and cultural suppressions as generating the vulnerability in individuals such as Hieronyma that made them targets for malicious spirits.

Hieronyma’s household continued to destabilize even as the list of eyewitnesses to the phenomena multiplied. Around Christmastime, the family hosted a group of military friends. Reportedly, the food, drink and place settings on their table disappeared in the blink of an eye; after a search, the party returned to the table to find it set with entirely different contents. In meticulous notes, Sinistrari documented the reactions of the family, servants and guests. The decanters and cups, as the professor recorded in his case notes, were filled with “foreign wines, from the Isle of Crete, Campania, the Canaries, the Rhine”; the appearance of which could not be explained.

Reports characterized further mischief. A small white wax lamb, which had been blessed personally by Pope Pius V, vanished. The entity, according to the family, swiped Hieronyma’s gold and silver from her jewelry boxes without breaking the locks. She also reported that her hollow silver cross, filled with small holy relics, vanished from her room. Furniture would be overturned and strewn about the house. Plates would appear to be smashed and then be repaired without a crack.

Consistent with Sinistrari’s theories, the entity, according to the family’s reports, behaved as though angry that Hieronyma had resisted it and remained faithful to her husband. It reached a crescendo one morning when the couple woke up in utter shock to find a wall of flagstones around their bed, reaching up to the canopy which hung over the four wooden posts. Friends had to bring a ladder for them to climb out of the bed.

Sinistrari’s methods took a different tack than the earlier priest who had tried to help Hieronyma. Sinistrari whispered his own sins before attempting a ritual. Carnal demons were empowered by vanity, so he had to accentuate humility. He kneeled before a crucifix, and recited Psalm 51, which began: “Have mercy on me, God, in accord with your merciful love; in your abundant compassion blot out my transgressions. Thoroughly wash away my guilt; and from my sin cleanse me. And protect your servant from pride.”

He would carefully remove a handful of rue leaves from his bag and bless the pungent-smelling herb known as the “herb-of-grace” due to its usage in the Catholic tradition. In Sinistrari’s usage, strong odors could attack the very source of these demons’ unusual powers and desires, their corporeal presence, and torment them.

The concoction now crumbled into ash. The room was silent, and the Bible would be tucked back into Sinistrari’s bag. The professor would have to temper expectations. He would hope the entity would be steered away, but as in all attempts to influence the spiritual realm, the case would be monitored.

Certain details from Sinistrari’s notes on the Hieronyma incubus case stood out as particularly unsettling, including the fact that Hieronyma was a loyal parishioner of San Michele Maggiore. It was named for and devoted to Saint Michael the Archangel, the angel who battled the devil and provided protection against evil. On the splaying of the left portal, or entrance door, of the 12th century sandstone church was carved a frieze of a two-tailed siren, an ominous warning specifically about sexual temptation. To a demonologist like Sinistrari attuned to every feature, the choice of a congregant of this particular parish came across as a flagrant dare to the whole church.

Sinistrari had ample opportunity to test the theory. Reported incidents came closer to clerical life, until crossing inside church walls. At one convent in the Lombardy region, two nuns, Sister Angela and Sister Maria, whose real names were concealed in case records, ended up at the center of a maelstrom that fell squarely into Sinistrari’s theological studies.

Angela and Maria lived in adjoining chambers in the convent. Angela heard strange noises at night from Maria’s room through the paper-thin walls. At first she thought she was dreaming, but the noises persisted. Angela also noticed that rather than go on evening walks in the garden with the other sisters, Maria would walk back alone through the dusk to her room.

One evening, Angela followed Maria back to their rooms. She leaned her head against the partition between the rooms, and heard the sound of creaking. Groans and sighs followed. Shocked and scandalized, Angela sneaked into the hall, but only saw Maria exit her room. At first, Angela was convinced Maria brought a man into the convent. But she realized it would have been all but impossible given the convent layout, and even though she had watched closely, she never saw anyone else enter or leave Maria’s room.

Angela informed the abbess, Sister Anna, the energetic and independent-minded director of the convent, about the incidents. The abbess gathered “discreet persons” and “confidants” to look into the situation. As an accomplished woman in the church, Sister Anna knew that suspicions of sexual transgression could be used as weapons against women. But bearing responsibility for the nuns’ safety and conduct, she had to consider every scenario, and Professor Sinistrari was the ideal candidate to evaluate a possible theological explanation to the apparently carnal encounters. Sinistrari, for his part, had a track record of being a kind and fair confessor, who avoided the mainstream tendency to blame or vilify women.

The impromptu investigators accompanied Sister Anna to Angela’s room, and heard the same noises coming from Maria’s chambers: heavy whispers, lumbering breaths, a shaking bed. Sister Anna stormed into the hall and knocked on Maria’s door. There was no answer; no movement could be heard in the room. The abbess called for it to be opened with a crowbar.

Then Maria opened her door, as though just woken up. “A search was made,” Sinistrari wrote in his case notes, “and no one [was] found.” There was no evidence that someone else had ever been in the room. Everyone agreed there had not been enough time for someone to sneak out, nor was there any other egress. Maria seemed as baffled as anyone else.

Angela, though, was not satisfied, and had a terrible feeling that something evil was happening, and that Maria could be in serious danger. She bore a hole in the thin partition wall between their cells. She would stake out the spot.

Sister Anna kept her loose committee of investigators on call. Sinistrari’s methods would include watching for a smoky aura to the demon’s body that would allow an incubus to appear and disappear into the air. Incubi, Sinistrari had chronicled, had the power “at will” to be “invisible to all but his mistress.” One of the only exceptions to the invisibility would be if the demonic presence was engaged in the act of intercourse, when it was possible for others to see the demon. If an incubus really was visiting the convent, Sinistrari would have seen it as the chance of a lifetime for his research into demonology.

While Sinistrari continued to compile his notes, he received a bizarre letter. It was not merely in another language—which the highly educated scholar could likely have translated—but rather written in caretteri ignoti, or unknown characters. As he labored to decipher the cryptic characters, the underlying message became clearer. In his interpretation, the document had somehow been produced by the demonic entity or entities he was chasing, a warning that the assault on the church was just beginning.

About six miles north of Sister Anna’s convent, at the massive, ornate Carthusian monastery at Pavia, the monks were guided by the expression Stat crux dum volvitur orbis: The cross is steady while the world turns. Carthusians lived their lives in silence. They abstained from meat. Their halls were devoid of music. They read, studied, wrote, gardened, worked a trade and prayed. They did not encounter the outside world, maintaining an unbreakable tranquility.

But one young monk named Augustine was in a panic. He had been overwhelmed with experiences of mysterious harassment; it was reminiscent of those reported by Hieronyma. One day, the prior, or director, of the monastery came to Augustine, committing himself to protecting his colleague from the devil. The prior urged Augustine to confess his sins so that he could remain pure of heart and promised that God would shield him. Augustine recited powerful selections of scripture with him, including John’s Gospel. When the prior reached the verse Verbum caro factum est et habitavit in nobis—the word became flesh and dwelt among us—he knelt in devotion. He sprinkled holy water around Augustine’s chamber and bed, and performed an abbreviated exorcism— exhorting the demon to leave Augustine alone. Suddenly, the prior vanished in front of Augustine’s eyes. In fact, as Augustine would discover, the prior had been elsewhere on the monastery’s campus all along. Augustine was certain he had just laid his eyes on the powerful demon taking on human form.

The vicar, or administrative official, of the monastery sent for Sinistrari with a plea for help. Rushing to the scene, Sinistrari met with the distraught Augustine, whom he described as “poor [man]” in his notes. He found the monk’s accounts chilling and credible, and also unprecedented in his demonology studies, glossing them as “unheard of ” in his case notes. Compiling all the events reported by witnesses at the monastery, Sinistrari determined that the demon was a shapeshifter, appearing not only as the prior, but also in animal forms as a pig, donkey, and bird; and in unnatural forms in visions, a skeleton and an angel. As a preliminary measure, Sinistrari prescribed concoctions that he had created to repel evil spirits, instructing Augustine to carry pills perfumed with musk, amber, chive, and Peruvian balsam, as well as tobacco and brandy also perfumed with musk.

Though the monastery phenomena did not manifest in reports of carnal assaults, they shared a continued pattern of invasion into a pious setting present in the cases of the dedicated parishioner Hieronyma and the convent nuns. Meanwhile, the bizarre, unreadable letter left for Sinistrari would continue to haunt him. In theological lore, there were two similar documents to consider. In 1634, priest Urban Grandier was burned alive for supposedly inviting a demon into the midst of nuns; a pact with the devil reputed to belong to him was found written in strange characters and signatures. Then, in 1667, a Sicilian nun wrote a letter that was said to be dictated from the devil, which would take centuries to try to decipher (it continues to be studied to this day by codebreakers). With Sinistrari discovering his document the next decade, it meant there were at least three coded letters related to suspected demonic activity in holy settings over a 50 year span. This supported a fear that the latest document and events were part of a larger spiritual coup against the church.

Sinistrari suspected that the demon with which they were dealing was indefatigable and could appear anywhere to any of its targets. As it turned out, the torments of Hieronyma had not ended. The demon visiting her household began taking on human form: a blond man with a golden beard and, as Sinistrari recorded in his notes, “sea-green eyes,” described as being dressed like a Spanish aristocrat. He was invisible to everyone but this woman, whom he continued to try to seduce at every turn, only to be enraged at the rejection.

Then came the assaults. Hieronyma reported being struck with great force by the demon, cutting and bruising her face, arms and chest. As reported by witnesses, lacerations and purple bruises would suddenly appear covering her skin, then vanish without a trace quicker than was humanly possible. She and her husband felt the world turned upside down. Then their daughter began to vanish. They would search everywhere before finding the girl in places the baby had no way of getting to, including the roof.

Heironyma was harassed beyond her endurance. Perhaps inspired by Sinistrari’s Franciscan methods, she decided to try to protect herself by wearing the frock of that religious order, tied with a cord around her waist. She wore the frock to Michaelmas, the feast for Saint Michael the Archangel, and gathered with others in preparation to enter the church for Mass. As she stepped on the threshold of the church door— beneath the sculpture of the devil— witnesses attested to a rush of wind that whisked off her frock, leaving her naked, all her clothing disappearing before their eyes. The incubus’ rage had turned into a public assault.

Back at the nuns’ convent, Sister Angela continued to observe Sister Maria’s chambers through the opening in the wall. Her patience paid off. Angela watched, clear as day, as Maria lay down on her bed with a handsome, well-dressed young man. It was the one time that people other than an incubus’ target could observe the demon.

Incubi and succubi were damned by their lust; in order to have sex with humans, they had to take on a material form, and yet in doing so, they could be defeated. But Sinistrari was not able to intervene to identify the incubi and help Maria because the abbess did not call for her committee of investigators. She had other plans. After Sister Angela rushed back to Sister Anna, the abbess burst into Maria’s room. Under serious threat of what Sinistrari later heard was “torture,” Maria confessed that she had submitted to an incubus.

Where the incubus had failed in its pursuit of Hieronyma, its intercourse with a nun imbued it with even greater and more destructive powers.

Through the startling accounts accumulated by Sinistrari, a potential demonic culprit emerged in a figure called Asmodeus. The entity was described in the Book of Tobit, an Old Testament text studied by Saint Augustine and Saint Thomas Aquinas. A woman named Sarah had seven husbands mysteriously killed by supernatural forces—said to have been slayed by Asmodeus, an especially cruel and powerful demon, before they could consummate marriage to her. The demon was presented as the prototypical incubus, wishing to have sex with Sarah and ready to kill any suitors in its way. Asmodeus was variably depicted as a gigantic beast or a well-groomed, aristocratic figure, similar to the figure described by Hieronyma and observed with Maria.

According to Sinistrari’s encyclopedic mastery of demonology, it now seemed that Asmodeus had set his sights on the clergy and pious people of Italy, a deeply Catholic place weakened by war and famine. The demon’s sweetest victory would be to conquer them—to rupture the ‘marriage’ (as it was sometimes referred to) between priests and the church or nuns and the church.

That master plan seemed to intensify at the Carthusian monastery, as the embattled monk Augustine struggled to try to fend off the demonic presence. The monk’s vicar, who had engaged Sinistrari in the case, was doing all he could to help. Augustine approached the vicar’s chambers and requested permission to obtain tobacco and brandy perfumed with musk in order to carry out Sinistrari’s instructions. Then, in a flash, Augustine disappeared—as though dematerializing— from the room. Augustine, in fact, was found to be elsewhere at the monastery. Sinistrari and the monastery’s officials concluded that the demon had “assum[ed] the features of his victim,” an ultimate taunt to them all.

If Asmodeus had taken on the prior’s identity and now Augustine’s, then Sinistrari could well be his next shape. If Asmodeus took on Sinistrari’s form, the demon could convincingly order a dangerous concoction that permanently opened Augstine’s soul to evil, and the monk would be lost forever. But if the scriptural account of Asmodeus introduced an early model of the incubus to demonologists, it also contained an example of the methods to defeat them with potent concoctions like those Sinistrari had been trained to create by the Franciscan friars. Included in the Book of Tobit was the character of Tobiah, who was the next man set to marry Sarah after Asmodeus had killed all her previous husbands.

The scripture described how a large fish attacked Tobiah in the Tigris River. The angel Raphael then appeared to him with these instructions: “Slit the fish open and take out its gall, heart, and liver, and keep them with you; but throw away the other entrails. Its gall, heart, and liver are useful for medicine.” Raphael further explained to Tobiah that the fish’s heart and liver were especially powerful: “if you burn them to make smoke in the presence of a man or a woman who is afflicted by a demon or evil spirit, any affliction will flee and never return.”

When Tobiah arrived at Sarah’s home, her family put on a great feast. Tobiah slipped away and removed the fish’s liver, gall and heart from his bag. He placed them on the embers in the bridal chamber, which had been prepared for incense. Tobiah made a fire, and the pungent smoke from the flame enraged Asmodeus, who had prepared to kill Tobiah for courting Sarah. The fumigation was too much for the demon, who fled to the mountains of Egypt.

This scriptural sequence demonstrated that Asmodeus, a demon driven ultimately by lust, could be cast away by natural substances properly manipulated to counteract his powers. Sinistrari had to bring all his specialized weapons to bear. He knew that the Roman Rite could not be deployed, nor would holy relics or the cross do the trick on their own.

Increasing the pressure on Sinistrari would be the worry—all the more acute due to his savvy as a canon lawyer—that his fumigation techniques would fall under the watchful eye of church hierarchy. Sinistrari’s methods were passed down carefully in Franciscan tradition, but the papacy in Rome had a skeptical view of the order’s idiosyncratic methods. There were whispers that Sinistrari’s methods were dangerous and that his fumigation techniques resembled something like dark magic.

Sinistrari had no intention of undermining the church, but to be safe he had to work in secrecy. If certain officials of the church discovered his actual methods, his mission would be stopped. Likewise, if the university realized the extreme work he was undertaking, he could lose his position at the law school.

Devising and preparing concoctions kept Sinistrari up at all hours, placing him under stress and physical strain. He refused to give up on helping the targets of the demon, and he refused to allow his spiritual nemesis to gain an even stronger foothold inside the church.Sinistrari had to summon his strength for one final battle.

Among his tools, Sinistrari could employ the so-called sixth method gleaned from the text of Menghi, the Franciscan priest who laid out the procedure of fumigation. It was a chance to liberate Hieronyma once and for all. Though Sinistrari typically would have used the method on possessed persons, it was applicable because the demon had effectively attached itself to the woman. In this process, Sinistrari would paint an image of Asmodeus surrounding Hieronyma. Sinistrari would then exorcize a blazing fire before dribbling some holy water into the flame. According to Menghi’s Franciscan tradition, Sinistrari then blessed a succession of materials— birthwort, St. John’s wort, galbanum, sulfur—before dropping them into the fire. Holding the painting over the fire, he would launch into lengthy insults, among them: “father of lies, traitor to all, root of all evil, origin of discord, instigator of vices, fool, senseless one, gossip, heretic, apostate, fetid, filthy, and evil being, devoid of any good and full of every evil, murderer, reprobate, son of perdition and of the eternal curse, enemy of mankind, you who tear life away and make justice deviate… recognize, then, your horrible sentence and your terrible punishment.” By listing names and descriptions of the evil spirit, he could strip away its deceit and disguises, exposing its true nature in order to defeat it.

Culminating with Sinistrari dropping the devil’s image into the roaring fire and watching it burn, the enemy was repelled from coming near Hieronyma. “Finding at last that he was losing,” Sinistrari recorded, the spirit abandoned his harassment of her.

To push their adversary out from the monastery where the monks had been under siege, Sinistrari prepared a complex formula for suffumigation including water lily, liver-wort, spurge, mandrake, house-leek, plantain and henbane. Sinistrari recorded the process of making “two little bundles of them and hang[ing] them up, one at [Augustine’s] window, the other at the door of his cell, taking care to [spread] some also on the floor and on the bed.” Sinistrari later recounted how the demon, vile and seething, appeared to him and the monk. It was the showdown with Asmodeus he had been preparing for through all the ordeals. The demon found himself unable to come closer. Augustine, taking back control of his life, jeered the demonic intruder, asking why he suddenly was so bashful. The demon screamed and cursed at Sinistrari before disappearing.

To believers, the entity had been expelled, at least for the time being, and Hieronyma and Augustine were freed from harassment. As for the nun, Sister Maria, Sinistrari was unable to debrief her. The abbess and other church authorities handed the disgraced nun over to the local bishop to be brought up on charges for giving herself to the incubus. But the authorities may well have not realized the extent of the deepest dangers of Asmodeus’s plans as understood by a demonologist. Sinistrari classified incubi, in taking human form, as “capable of breeding.” He believed that the offspring of woman and incubus could be “an intermediate species between the demon and man,” and could even become the antichrist. It remains unclear if Sister Maria ever became pregnant or gave birth. Whatever Sinistrari might have tried to do to help her, he, too, would be blocked from accessing her. No records survive that chronicle Maria’s ultimate fate, and the convent was soon closed down, with much of its history disappearing.

Meanwhile, the case had taken its physical and emotional toll on Sinistrari. He had fought what felt like a thousand battles, traveling to and from towns and villages to carry out his investigations. He developed a serious case of gout. He continued to serve the church, including in several high official positions, and he still taught and practiced law. At one point he defended a priest who was alleged to have communicated with the dead.

But he knew the time had come to pass on his methods. He returned to the mountain monastery where he had first witnessed a Franciscan exorcism before becoming the master of those methods. Among these surroundings, he turned his attention to compiling his theology and accounts in a manuscript called De Daemonialitate— ‘The Demoniality.” That manuscript would be hand-copied for years by scribes and monks as an exorcism before disappearing into history, until it was spotted in the London bookstore by Isidore Liseux, who began an almost obsessive quest to bring it to the public.

Epilogue

1934: London, England

The rhythmic knocks soon became pounding fists against the door. The police threatened to arrest everyone inside if the door was not unlocked. The staff had little choice; they unlocked the door and stepped aside as the police confidently entered the room.

The police raided Fortune Press, a small publisher, with a ruling in hand. The magistrate called their ambush a “public duty.” They were there to cleanse the world of a sinful book.

More than 60 years after Liseux had rediscovered it, the police seized all copies of De Daemonialitate in the name of the Obscene Publications Act. The publisher quipped that they were burning a priest’s book. They did not heed his warnings and destroyed them all. Ultimately, Sinistrari’s work and its reliance on esoteric demonology also caused him to land on the Catholic Churches’ infamous list of banned works, an ironic twist considering how much the church had depended on him and his methods. Today, the rare printed editions of De Daemonialitate are mostly found on the shelves of theological and legal scholars and perhaps historians of sexuality. The Catholic tradition of demonology continues to the modern age; in a 1972 general address, Pope Paul VI insisted that the devil was real, not a symbol or “a conceptual and imaginary personification of the unknown causes of our ills,” and to think otherwise departs from biblical and church teaching.

The original manuscript of De Daemonialitate, and many of Sinistrari’s additional chronicles and notes (including the coded message he believed to be demonic, which he kept locked away), have been lost to history—or perhaps like his book had for so many centuries they remain in the hands of trusted experts, as guides to battle the most dangerous demons.

Nick Ripatrazone has written for Rolling Stone, GQ, Esquire, The Atlantic, & is the Cultural Editor for Image.

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