Yoga has become one of the most popular exercise routines in America, as well as a big business: $10.3 billion is generated each year from this growing industry. While hundreds of styles and philosophies have emerged from this Indian discipline, a writer named Patanjali set the stage in the second century when compiling the Yoga Sutras. While most Americans begin with his third rung, asanas (postures), the first two are little discussed: the yamas...