Yoga is everywhere these days: Hollywood stars take their personal instructors with them on location; newspapers and magazines hail yoga as the answer to the unrelenting stress in our society; and gyms everywhere are now offering a dizzying array of classes. The yoga we practice today in the West bears little resemblance to the yoga that began humbly almost 5,000 years ago, but in its rich and varied history, yoga has always evolved to meet the needs of the culture it serves.