"Yin Yoga" would appear to be a classic post-modern mash-up, combining Indian yoga with Chinese Daoism as a way to appeal to modern westerners. Bernie Clark's book, YinSights: A Journey into the Philosophy & Practice of Yin Yoga, attempts to show how these various traditions work together to provide a useful an necessary balance to the typically yang-style yoga done in the west today.
Clark's method appears simple. He examines the physical body, energy and psychology through the lenses of yogic thought, Chinese medicine, and western science. Each area is, in itself, a large topic, and Clark must necessarily pick and choose his models and ideas. So while he may elide some distinctions and paint similarities with too broad a brush, he is to be commended for attempting to look at these various traditions in a way that tries to honor them all. He meticulously footnotes his sources, so interested readers can follow his thought, whether the topic is a yoga asana or the thought of Carl Jung.
He begins with a brief history of the modern movement known as Yin Yoga. He highlights his main influences--Paul Grilley, Sarah Powers, and Dr. Hiroshi Motoyama--all of whom appear multiple times throughout the book. The major portion of the book is dedicated to the philosophical underpinnings. Finally, in the last section of the book, he describes the asanas used in Yin Yoga, explains how they are modified and how long they are held, and then provides several examples of flows that constitute a practice of Yin Yoga.
While all the philosophy is interesting, I couldn't help but feel that a book dedicated to this practice would have been better served by giving more space to the asanas and practices. Nevertheless, the book provides a good starting point for someone interested in Yin Yoga, and gives enough depth to those interested in the more esoteric philosophies that inform it. Bernie Clark maintains a website at http://www.yinyoga.com that provides more information and suggestions for yin yoga practice.