A sworn enemy of superstition, Canadian-born magician James Randi has thrown down the gauntlet to mystics, promising a million dollars to anyone who can prove supernatural powers or a phenomenon beyond the reach of science. An arch-sceptic who demonstrates with his own sleight of hand how easily it is to dupe the gullible into mistaking trickery for the supernatural, the bearded 76-year-old has written nine books and lectured at the White House, NASA and several top U.S. universities. The million-dollar "paranormal challenge" lends publicity to Randi's life-long mission. His pursuit of scepticism was sparked by a visit to a spiritualist church in his native Toronto when he was just 15. Already an amateur magician, he was upset at seeing "common tricks" pass for divine intervention. But his attempts at enlightening the churchgoers cost him four hours questioning at the police station. Sixty years on, Randi is still trying to persuade people to give up their belief in mystic forces beyond their control. "It's a very dangerous thing to believe in nonsense. You're giving away your money to the charlatans, you're giving away your emotional security, and sometimes your life," he explained in an interview before giving a lecture in Stockholm. Deeply concerned with the spread of beliefs not based on the principles of science, Randi is especially worried about the growing popularity of exotic cures and therapies catering to sick people who are then lured away from effective treatments. "It's a mission, and also an obsession," he said. The challenge also serves to dent the image of professional psychics, as they so far have balked at the chance to win the million. "They offer all kinds of strange excuses," he said. On a European tour of Germany, Italy, Ireland, Belgium and Sweden, Randi tested people who wanted to go for his million. Most applicants sincerely believe they have supernatural gifts, the vast majority claiming to possess the power of dowsing -- the ability to detect water with the help of a cleft stick. Dowsing has never been proved to work in a controlled setting, said Randi. "But no one ever changes their mind," he said, recalling only one single case throughout the years where a man backed down from his claim after being tested. At a lecture to promote critical thinking, a Swedish audience of about 300 applauded and laughed as Randi blasted away at astrologers, homeopaths, faith healers and psychic mediums, accusing them of defrauding the sick and the desperate. Riddling his performance with tricks -- divining the symbols on cards put in an envelope by an apparently randomly-chosen audience member -- Randi says his own expertise at "magic" helps him expose fraudsters.