The answer was no longer a simple matter of faith. As Stephens notes, all of this turmoil coincided with a time of intense questioning by theologians who were schooled in Scholasticism, the dominant philosophical doctrine of the time in Europe. They struggled to reconcile the literal text of Scriptures with what they understood of physical reality by reading from Aristotle and other protoscientific texts. Prior to around 1200, most Christians held what Stephens calls the "uncomplicated belief in the reality of devils, angels, and the whole world of spirit." All of that was in the Bible, they were told, so they simply believed. Two hundred years later, belief was no longer so uncomplicated. Scholastic theologians pored over the Bible and asked, Why are there no more miracles? How was the Flood possible? That is, how could it really have happened? For example, what did God do with all of the water afterward? How did Noah get enough feed for the animals on the Ark? These questions may remind a modern reader of the insistent queries from children in Sunday school, but in the 15th century, some of Europe's best-educated minds were wrestling with them. Says Stephens, "There's this increasing rationalism among theologians. The Bible needs to be explained on a literal level, not as allegory, when stacked up against what they know of the world."

Among the many things accomplished by the book is a vivid rendering of the witch hunts' context. The earliest documentary evidence of an actual European witch trial (not trials for heresy or sorcery, which did not necessarily involve corporeal interaction with demons) is circa 1430. The sanctioned, organized pursuit and persecution of witches, which peaked from 1560 to 1630 and was almost entirely a western European phenomenon, began during a time of grave concern in the Roman Catholic church. The European world in the early 1400s was a wreck. The preceding century has been labeled by historian Barbara Tuchman as "calamitous," and she does not overstate. Starting around 1315, a great famine ravaged much of western Europe. From 1347 to 1352, the Black Death killed more than a third of the continent's population. Other diseases and additional outbreaks of the plague scourged the weakened survivors. As if natural catastrophe weren't enough, England and France chose to fight the Hundred Years' War from 1337 to 1453, the longest war in history. The Church itself fractured, riven by massive organized heresies, and by a schism that led to as many as three men simultaneously laying claim to be the true pope. How could a world created by a watchful, benevolent, and engaged God be such a mess?

On the desk of his Gilman Hall office, next to a Macintosh computer that announces the arrival of new e-mail seemingly every 10 minutes, Stephens has a paper witch. It's a Halloween decoration, so she's decked out in a long black witch's dress, with her traffic-cone hat and magic broom. Stephens can look devilish himself, favoring black jeans, a distressed leather jacket, and a black fedora. He has just published his new theory in the alluringly titled Demon Lovers: Witchcraft, Sex, and the Crisis of Belief (University of Chicago Press, 2002). It's a dense but engaging volume, praised by Umberto Eco as "a work of high and fascinating scholarship on a story which has frequently inspired only legends and occultism."

Stephens' thesis profoundly revises the conventional wisdom about centuries of cruelty and injustice. The great European witch hunts, he says, were the outgrowth of a severe crisis of faith. The men who wrote books like the Malleus , men who endorsed the torture and burning of tens of thousands of innocent people, desperately needed to believe in witches, because if witches were real, then demons were real, and if demons were real, then God was real. Not just real but present and attentive. Carefully read the works composed by the witchcraft authors, Stephens says, and you will see how profoundly disturbed these educated, literate men were by their accumulating suspicions that if God existed at all, He wasn't paying much attention to the descendants of Adam.

For the next eight years Stephens read every treatise he could find on witchcraft, as well as accounts of interrogations, theological tracts, and other works (his bibliography lists 154 primary and more than 200 secondary sources). Most of the 86 witchcraft treatises he cites had been written in western Europe in the 15th, 16th, and 17th centuries, and one after another (including the Malleus ) contain accounts of sexual intercourse with satanic spirits. Why? Were the authors remorseless misogynists hellbent on portraying women in the worst possible light? Were they lurid, repressed celibates who got off by writing accounts of demon sex? Stephens didn't think so; the texts, in his view, didn't support that reading. Elsewhere in the Malleus he had found a key reference to accused witches under torture as being "expert witnesses to the reality of carnal interaction between humans and demons." These guys are trying to construct proofs that demons exist, he thought. They're trying to convince skeptics. And then he thought, They're trying to convince themselves.

Stephens, the Charles S. Singleton Professor of Italian Studies in the Hopkins department of romance languages , is a literary critic, and he sensed that something intriguing was going on beneath the text on the page. Tasso, and especially the Malleus' author, a Dominican theologian and inquisitor named Heinrich Kramer, had in their works invested a striking amount of energy in refuting doubt about the existence of demons. What was that about?

That convoluted sentence dovetailed with a curious line Stephens knew from Il messaggiero, a work from 1582 by the Italian poet Torquato Tasso: "If magicians and witches and the possessed exist, demons exist; but it cannot be doubted that in every age specimens of the former three have been found: thus it is unreasonable to doubt that demons are found in nature."

"It was 11 at night," Stephens recalls. "My wife had gone to bed, and on the first page [of the Malleus ] was this weird sentence about people who don't believe in witches and don't believe in demons: 'Therefore those err who say that there is no such thing as witchcraft, but that it is purely imaginary, even although they do not believe that devils exist except in the imagination of the ignorant and vulgar, and the natural accidents which happen to man he wrongly attributes to some supposed devil.'"

But by the 15th century, troubled theologians seeking proof of the existence of spirits had become attentive to stories of witches. The poor illiterate, ignorant peasants still simply wanted an explanation for why their wheat had fungus or their new baby, seemingly healthy, had died the night before. The learned theologians, says Stephens, had something else in mind. The confessions of accused witches were useful if taken as the expert testimony of people who knew demons existed because they hadn't just seen them, or heard them -- they'd had sex with them. Intercourse with one of Satan's own met even Aristotle's tough standard for experiential evidence, or so the theorists wanted to believe. "Sex with demons was so important because it was the most intimate form of physical contact imaginable," says Stephens. "You can't have sex with something imaginary."

"Sex with demons was so important because it was the most intimate form of physical contact imaginable. You can't have sex with something imaginary."