To some, “haunted houses” might seem like nothing more than a scary superstition. But the phenomenon has actually been the source of serious spiritual study for hundreds of years, says Biola professor Robert Llizo, who was recently commissioned to translate one of the most cited works on the matter: “Loca Infesta.” Peter Thyraeus’ 411-year-old work, “Loca Infesta,” is commonly referred to by scholars working in the field of medieval and early modern notions of demon possession, magic, hauntings, and witchcraft, but has never been translated from Latin until now.

While reading a copy of the “Rule of St. Benedict” at a church retreat, Llizo was approached by the Rev. George Aquaro, who noticed Llizo was actually reading in Latin. Aquaro, who was coordinating a group of scholars to translate Latin treatises on angels and demons, asked him if he would be willing to take up the task of translating the 1599 document “Loca Infesta.”

“Loca Infesta” or “On Infested Places,” discusses haunted houses and places in relation to how to handle them. The project, commissioned by the Catholic Archdiocese of Pittsburg, and overseen by the chief exorcist of the Vatican, was spurred by a rising need for priests and ministers to be knowledgeable on exorcisms and demons.

Llizo answered a few questions regarding the daunting project.

What inspired your interest in "Loca Infesta"?

Llizo: In my doctoral research on St. Francis and the urban ascetic tradition, a common theme seemed to emerge: the ascetic's confrontation with the devil or with demons in his search for union with God. There is a strong element of spiritual warfare associated with much of the literature that I've read. What got me interested in Thyraeus' work was reading St. Gregory the Great's "Dialogues" about a certain Bishop Datius of Milan (ca. 530) who, on his way to Constantinople in order to support Pope Vigilius against the Emperor Justinian, stopped by a house in Corinth believed to be haunted by Satan and his demons. With no fear whatsoever, he took up residence there, and exorcised the place, reclaiming it for Christ. Thyraeus' work is a manual for priests showing them how to do just that when they encounter houses or buildings that are haunted by spirits. When I was tapped to translate "Loca Infesta," I had just read that section of the Dialogues, and so I jumped at the chance.

What can you tell us about Peter Thyraeus and why this work is still referred to by scholars today?

Llizo: Peter Thyraeus was a late sixteenth-century German Jesuit theologian (d. 1601). He taught at the University of Wurzburg from 1590 until his death. He was quite a prolific writer, writing on subjects ranging from spirits, demons and exorcism to the nature of the Eucharist. His work on exorcism is deemed to be the first "scientific" or systematic study of the nature of demon possession, influencing many modern practices of exorcism.

For what reason did the Catholic Archdiocese and chief exorcist of the Vatican decide to commission the piece to be translated now?

Llizo: Fr. Gabriele Amorth, the Chief Exorcist of the Diocese of Rome, sees a growing need for priests to be armed with an ability to be able to confront demonic manifestations, whether they be in people or in places, and for the wider Christian public to be able to understand that however "sophisticated" and "modern" we are, demonic manifestations are real. C.S. Lewis sounds a cautionary alarm that I keep in mind as I undertake my work of translating this text: "There are two equal and opposite errors into which our race can fall about the devils. One is to disbelieve in their existence. The other is to believe, and to feel an excessive and unhealthy interest in them." Perhaps many modern Christians may confess belief in angels and demons, but in fact act as though like the wider secularized society that disbelieves in their existence. But we must also not be so curious about their activities, but only insofar as they can affect us. This is where prayerful watchfulness comes in, which is a common theme in a lot of patristic literature. I think the purpose for the writing and translating of these texts is to inspire a sense of prayerful watchfulness over our hearts, so that our hearts can be always turned towards God, not giving any occasion for the devil and his minions to take residence in our lives.

What do you find particularly intriguing about “Loca Infesta”?

Llizo: The interesting thing about this work is that it deals with haunted houses and places, and how to deal with them. Peter Thyraeus speaks of this as an "infestation," much as you would speak of a roach or rat infestation. What I like about Thyraeus is that he is quite no-nonsense about it: If one finds oneself in a situation where there are spirits haunting a house or a building, there are instructions for how to deal with them. One thing that he prescribes is Psalmody, and lots of it. It seems that when one is dealing with a demonic situation haunting a place, reciting Psalms is almost like throwing acid at the demons. If you ever wondered what the imprecatory Psalms were for in a Christian context, Thyraues can answer that question quite clearly: Use them against the enemies of your soul, Satan and his demons. Another thing I like about the "Loca Infesta" is that there is nothing "fantastic" about it, unlike the "Malaeus Maleficorum" (The Hammer of the Witches), with fantastic stories about demon children born to witches. Thyraeus takes a more self-consciously theological approach to the question of hauntings and possession. While his thoughts on human spirits haunting a place being the souls of those bound for Purgatory might be problematic, his work on demonic manifestation, whether in people or in places, is spot on and should be made available to a wider audience. It is the most cited work by scholars working in the field of medieval and early modern demonology and witchcraft, but it has never been translated.

Written by Jenna Bartlo, Media Relations Coordinator. Jenna can be reached at (562) 777-4061 or through email at