Stars do it. Sports do it. Judges in the highest courts do it. Let’s do it: that yoga thing. A path to enlightenment that winds back 5,000 years in its native India, yoga has suddenly become so hot, so cool, so very this minute. It’s the exercise cum meditation for the new millennium, one that doesn’t so much pump you up as bliss you out. Yoga now straddles the continent–from Hollywood, where $20 million-a-picture actors queue for a session with their guru du jour, to Washington, where, in the gym of the Supreme Court, Justice Sandra Day O’Connor and 15 others faithfully take their class each Tuesday morning. Everywhere else, Americans rush from their high-pressure jobs and tune in to the authoritatively mellow voice of an instructor, gently urging them to solder a union between mind and body. These Type A strivers want to become Type B seekers, to lose their blues in an asana , to graduate from distress to de-stress. Fifteen million Americans include some form of yoga in their fitness regimen–twice as many as did five years ago; 75% of all U.S. health clubs offer yoga classes. Many in those classes are looking not inward but behind. As supermodel Christy Turlington, a serious practitioner, says, “Some of my friends simply want to have a yoga butt.” But others come to the discipline in hopes of restoring their troubled bodies. Yoga makes me feel better, they say. Maybe it can cure what ails me. Oprah Winfrey, arbiter of moral and literary betterment for millions of American women, devoted a whole show to the benefits of yoga earlier this month, with guest appearances by Turlington and stud-muffin guru Rodney Yee. Testimonials from everyday yogis and yoginis clogged the hour: I lost weight; I quit smoking; I conquered my fear of flying; I can sleep again; it saved my marriage; it improved my daughter’s grades and attitude. “We are more centered as a team,” declared the El Monte Firefighters of Los Altos Hills, Calif. Sounds great. Namaste, as your instructor says at the end of a session: the divine in me bows to the divine in you. But let’s up the ante a bit. Is yoga more than the power of positive breathing? Can it, say, cure cancer? Fend off heart attacks? Rejuvenate post-menopausal women? Just as important for yoga’s application by mainstream doctors, can its presumed benefits be measured by conventional medical standards? Is yoga, in other words, a science? By even asking the question, we provoke a clash of two powerful cultures, two very different ways of looking at the world. The Indian tradition develops metaphors and ways of describing the body as it is experienced, from the inside out. The Western tradition looks at the body from the outside in, peeling it back one layer at a time, believing only what it can see, measure and prove in randomized, double-blind tests. The East treats the person; the West treats the disease. “Our system of medicine is very fragmented,” says Dr. Carrie Demers, who runs the Center for Health and Healing at the Himalayan International Institute of Yoga Science and Philosophy of the USA in Honesdale, Pa. “We send you to different specialists to look at different parts of you. Yoga is more holistic; it’s interested in the integration of body, breath and mind.”