Within the Yoga Sutra, an ancient text about the practice of yoga, only two verses mention asanas, or the postures we commonly associate with yoga in the West. Patanjali, the legendary sage and author of this 2,250-year-old work, was concerned not solely with physical development, or even mental development. In fact, the original purpose of yoga was--and remains--to function as a complete spiritual path where the body serves as a gateway to enlightenment. On...