'The Vatican Prophecies' by John Thavis Courtesy of Penguin Random House

The long history of the Catholic Church is dotted with elements that border on the supernatural: miracles, apparitions, visions of the Virgin Mary. Even exorcisms, which have captured the public imagination through movies, are part of church doctrine.

But as longtime-Vatican journalist John Thavis notes in his new book, the modern Vatican often shies away from talk of such topics for fear of being dismissed as a fringe element. Thavis explores this in his newest book, "The Vatican Prophecies: Investigating Supernatural Signs, Apparitions and Miracles in the Modern Age."

With the Internet and social media, events like an image of the Virgin Mary appearing on a wall can go viral before any Church official even knows it happened, making it hard to investigate and manage such reports.

"Most Vatican officials don't want to hear about this stuff," Thavis said "If it's a serious thing, it requires investigation and patience. And if it's not a serious thing, it requires the Vatican to curb people's enthusiasm."

Thavis joined MPR News' Tom Weber to discuss the Church's &madsh; and the Pope's — modern approach to the supernatural.

On relics

Centuries ago, it was common practice for every Catholic church to have a relic in its altar — a piece of a saint's body, or even a drop of a saint's blood. Relics from saints were valuable commodities; Thavis recounted the story of a priest who once exhumed a saint's body, and wore her finger around his neck for the rest of his life.

When Catholicism was predominantly confined to Europe, Thavis said, "they had enough relics to go around." As the religion spread, however, the availability of relics became an issue.

Now, Thavis notes, "the Vatican has moved away from cutting up saints' bodies." Altars no long require relics. In his research, Thavis visited a convent in Rome where the nuns prepare ancient bones for distribution. They told him they were running out of material, as the Vatican wound down the practice.

That doesn't mean interest in relics has decreased, though. Millions of tourists still flock to churches around the world who hold — or claim to hold — relics.

Relics currently on display put the Catholic Church in a difficult position. Many are false, but even when the Church suspects as much, it is hesitant to interfere and upset local beliefs.

"The Vatican is not going to step in and say: 'By the way, what you have been venerating for hundreds of years is probably not really the brain of St. Peter.'"

Visitors welcomed the relics of Saint Therese of Lisieux in Westminster Abbey in 2009. Relics of a 19th century Roman Catholic nun described by some as the "greatest saint of modern times" toured England and Wales for a month. AFP/Getty Images

On the investigation of miracles

By definition, miracles defy logic. But the Vatican applies its own logical, systematic procedure for investigating them. The Church, Thavis notes, has an office staffed with people whose job it is to vet potential miracles and make sure they can withstand scrutiny.

"They mainly rely on medical evidence," Thavis said of the investigators. "Most of the miracles that happen now are medical miracles: healing that has no medical explanation."

The Vatican consults with its panel of medical experts and theologians to verify the event. To date, Thavis said, the office is very proud of its track record.

"They are proud that they throw a lot of these cases out, and only the real ones get through."

On exorcisms

Play the first three seconds of the score to the 1973 film "The Exorcist" and most American adults know what's coming. The classic film burned terrifying images of exorcisms into the brains of a generation: thrashing, screaming, head-spinning, pea soup terror.

"We have a Hollywood understanding of it," Thavis said of the Catholic exorcism rite. In reality, he said, most exorcisms are calm events — they're settled with prayer and putting a crucifix near the body of the person thought to be possessed.

In 1999, the Vatican came out with a new exorcism ritual which further toned down the old rite. It asked priests to go calmly about their business, to "almost politely ask that the devil leave," Thavis said.

But not everyone agreed with the move. Some exorcists complained that the new rite was in vernacular language. "I've had exorcists tell me: 'Look, the devil understands Latin, not English."

That's the situation the Catholic Church faces: How to adapt to modern times without alienating those who believe strongly in the more mystical elements of the religion.

This question becomes particularly critical when it comes to the Church's goals of expansion, Thavis notes. Catholicism stands to grow its following by connecting with believers in parts of the world where supernatural signs are commonly accepted, or even revered, in daily life. This runs in contrast to its recent approach to the supernatural.

How will the Church balance this? Followers are waiting to see.

Pope Francis is due to visit the United States for the first time on Sept. 22. Thavis will be covering the Pope's scheduled stops in Washington, D.C., New York City, and Philadelphia. The supernatural probably won't be high on his list of subjects to address.

"We know more about his position of climate change than we do about his thoughts on apparitions."