Yoga is now as mainstream as Madonna, as indispensable to fitness culture as the StairMaster. In Yoga: The Path to Holistic Health, 82-year-old Yogacharya B.K.S. Iyengar (Light on Yoga The Tree of Yoga), one of the worlds leading yoga teachers, makes it even more accessible, offering detailed instructions for postures of all levels of difficulty, illustrated by color photos and accompanied by helpful explanations of their health benefits. The basic Adhomukha Svanasana (Sanskrit for downward-facing dog posture) stimulates the nervous system, while the more daunting Salamba Sirsasana (headstand) promotes clarity of thought and improves your memory. Other postures, according to Iyengar, boost the respiratory and immune systems, tone muscles and, most important, relieve stress. Not only a how-to, Iyengars book also includes a concise explanation of yogas spiritual dimension