AT THE climax of the 1973 horror movie The Exorcist, the possessed girl's head spins full circle, she shows superhuman strength and levitates, as two priests say prayers and command the demon to leave her.
While, like any movie, it is sprinkled with dramatic licence, the scene, as Father William Goh describes it, is not that far removed from the truth.
According to the Catholic theologian at the St Francis Xavier Major Seminary, the act of exorcism does indeed involve reciting prayers and commanding the invading spirit to leave its host. And the possessed can demonstrate unnatural strength and power.
But one thing the movie does not show is the lengthy preparation that goes into an exorcism. Father Goh said the ritual, which he calls 'solemn exorcism', is not something that can be performed ad hoc.
A team must first agree that the person is possessed, which can mean sending him or her for psychological evaluation. Only then can a priest specially appointed by the bishop carry out the exorcism.
To his knowledge, it has never happened here.
For all its portrayal in popular culture, exorcism is still a rather mysterious practice.
Last week, however, it was thrown into the spotlight by the case of Madam Amutha Valli, a 50-year-old woman who is suing priests for what she claims are the side-effects of a botched exorcism to which she never consented. The two clergymen from Novena Church deny the charges.
Different religions take varying approaches to exorcism.
For Catholics, any exorcism must involve certain key principles.
Preparation is a significant part of the ritual, with priests undertaking prayers for repentance, divine intervention and protection before engaging in the ceremony. Post-ritual, the victim must also go through counselling to enhance his spiritual life.
The act of exorcism itself is simple and involves commanding the demon out of its host by invoking the power of God.
Father Goh said: "They may use words like 'In the name of Jesus, I command you to leave this creature of God.' It is a command, not a request."
He stressed that they do not physically restrain the possessed person.
Buddhists take a different line. Said Mr Shen Shi'an, chief editor of the Web and library departments at the Kong Meng San Phor Kark See Monastery: "Buddhist exorcism does not aim to kill, trap, hurt, or chase away harmful unseen beings."
The prayer and meditation is carried out for the purpose of persuading the spirit to leave the body.
"Buddhist exorcism aims for win-win situations for the involved human and spirit - who are seen as two parties negatively affected by grudges that require peaceful negotiation," he said.
Taoists, meanwhile, mainly use chanting, prayer and physical movements to fight the evil spirit.
Master Tan Kok Hian, vice-president of the Taoist Federation (Singapore), said: "We believe that there is good and there is evil, and the evil spirits will usually run away when they are faced with good."
Among Muslims, belief in possession is not universal.
Mr Nazirudin Mohd Nasir, head of the Office of the Mufti at the Islamic Religious Council of Singapore, said: "We believe there are unseen creations of God such as the 'jinn'." Jinn are similar to spirits.
"One could possibly be possessed by the unseen, but one should not simply blame everything on this. In fact, some people do not believe in possession, although they believe that the unseen exist."
The important thing for Muslims, said Mr Nazirudin, is "to enhance their spirituality, so that they have a strong spiritual self to thwart all forms of disturbance".
For Muslims who do believe, however, he said there were those in the community who specialised in the exorcism ritual.
One 47-year-old teacher, who did not want to be named, told The Sunday Times of her encounter last year with possession.
"Half an hour before it happened I felt something inside me, like I was pregnant," said the mother of three daughters.
"When it happened it was like somebody was trying to suffocate me from the inside. Then it was like I had no control of my body. I could see out, but I was caught in this box."
Her family remembered her screaming for hours on end and then abruptly going quiet. Yet, when they took her to the hospital, all her vital signs were normal. "The doctor told us to look for other treatment," she said.
That was when they called a spiritual healer. The ritual, which involved reading passages from the Quran, seemed to cure her. All in, the ordeal lasted a day.
Consultant psychiatrist Brian Yeo is rather sceptical about possession. He said he sees one patient every two to three weeks who is supposedly possessed, and more during the Chinese seventh month.
For him, behaviour such as that described by the teacher could be explained medically as entering a hysterical trance state.
"The symptoms are the same, it's just the cause that is different. Such a state might be triggered by stress," he said.
"When I see someone levitating, speaking in fluent Portuguese and telling me tomorrow's 4D results, then I'll be totally convinced, but for now let's just say I won't rule out possession completely."
This article was first published by The Straits Times on Sep 3, 2006