Father Amorth was born Gabriele Amorth, the son of a lawyer, in the town of Modena, in the north of Italy. In his teens, during the Second World War, he joined the Italian Resistance, and then he became Giulio Andreotti's deputy in the youth wing of the Christian Democratic Party, a Roman Catholic centrist party. He left that position and was ordained in 1951. In 1986 he was assigned by the vicar of Rome to assist Father Candido Amantini, then the chief exorcist in Rome. When Father Amantini died, in 1992, Father Amorth was named his successor. In the years that followed he has variously been referred to as "the Vatican Exorcist," "Rome's chief exorcist," and "the Dean of Exorcists." He has performed thousands of exorcisms successfully, and in 1990, he founded and led the International Association of Exorcists. Currently there are 4 exorcists in Rome and some 300 around the world within the Catholic Church, Father Amorth said, many of them trained by him.

I had been curious to meet Father Amorth for many years. In the early 1970s, when I directed the film The Exorcist, I had not witnessed an exorcism. Maybe this would be an opportunity to complete the circle, to see how close we who worked on the film came to reality or to discover that what we created was sheer invention.

I am an agnostic. I believe the power of God and the human soul are unknowable. I don't associate the teachings of Jesus with the politics of the Roman Catholic Church. The authors of the New Testament--none of whom, it is now generally believed by historians, actually knew Jesus--were creating a religion, not writing history.

I had no particular interest in the spiritual or the supernatural when the writer Bill Blatty asked me to direct the film of his novel, The Exorcist. Six years before, I had told him one of his scripts was terrible. As a result, he believed I was the only director who would tell him the truth. We didn't know each other well at the time, and I had no credits that would suggest I could manage a difficult film such as The Exorcist. Then my film The French Connection opened successfully and the studio came on board.

Blatty had started writing his novel 20 years after hearing about a case of possession involving a 14-year-old boy in Cottage City, Maryland. The case had been chronicled at great length in 1949 by The Washington Post, which quoted Catholic sources saying that the boy had been possessed and was successfully exorcised. The reporter, Bill Brinkley, was given extraordinary access to the Washington, D.C., diocese. But Blatty, then an undergraduate at Georgetown University, couldn't get anyone involved to divulge the facts of the case, so he wrote it as fiction and out of his own deep faith.

Blatty and I wanted the film to be as realistic as possible, with the flavor of a documentary. We had a technical adviser for the exorcism scenes, Rev. John Nicola, assistant director of the National Shrine of the Immaculate Conception in Washington. He was considered an expert on the ritual, though he had never seen or performed one himself--few people, including priests, have.

More than any film I've directed, The Exorcist inspired me to the point of obsession each day as I made it. I rejected all constraints, creative and financial. The studio, Warner Bros., thought I had taken leave of my senses. I may have. I made the film believing in the reality of exorcism and never, to this day, thought of it as a horror film.