The hulking security guards standing at the side of a Hunter College lecture hall was a big hint that their usual professor might be taking the afternoon off. When the lights came up and Madonna walked in, that confirmed it. The pop icon surprised students at a film course who had just seen an advance screening of her tour documentary, I'm Going to Tell You a Secret. Her appearance was filmed for the mtvU network series "Stand In," where celebrities such as Marilyn Manson, Bill Gates, Shimon Peres, Melissa Etheridge and Kanye West have appeared as guest lecturers at colleges. Asked by a student what drove her to succeed, the 47-year-old pop star said, "It's one of those things you can't really answer. You're either hungry and determined to make it, or you're not. I know a lot of people who, when they got rejected, they accepted what people said about them. I never did that." Madonna, who was raised a Roman Catholic, said she was led toward Jewish mysticism following a spiritual quest that began when she had children. "Being a celebrity, you can get very caught up and seduced into believing and thinking that what you do is the most important thing in the world and get very attached to material things," she said. "I'm guilty of that and I'm still guilty of that, but hopefully I'm becoming less attached." When she studied Kabbala, it was the first time she felt encouraged to ask questions. "Kabbala may not be the best thing for everybody," she said. "It has worked for me." On a separate occassion, Madonna made more inflammatory remarks about the material world. Speaking with a TV documentary she said: "People are going to go to hell if they don't turn from wicked behavior. The material world... the physical world, the world of illusion that we think is real, we live for it. We're enslaved by it. It will ultimately be our undoing." Madonna launched a scathing attack on modern society - claiming people will go to hell if they don't mend their "wicked" ways, calling the western world "The Beast," chasing illusionary dreams that ignore the real issues.