David Carpenter & Ian Whicher 
Yoga [PDF ebook] 
The Indian Tradition

The popular perception of yoga in the West remains for the most part that of a physical fitness program, largely divorced from its historical and spiritual roots. The essays collected here provide a sense of the historical emergence of the classical system presented by Patanjali, a careful examination of the key elements, overall character and contemporary relevance of that system (as found in the Yoga Sutra) and a glimpse of some of the tradition’s many important ramifications in later Indian religious history.