The Western view of Hatha Yoga treats it as an exercise program for the most part, and most people do not put serious thought into the detailed knowledge, not only of anatomy and physiology in evidence in the Asanas or postures that have been developed, but of the relation between the energy flow of the body as determined by these asanas and the accompanying control of the vital force and the psychological, mental and spiritual impacts that can be achieved.
Western science has begun to recognize the real health benefits that can accrue from the practice of Hatha Yoga, which means an understanding of the science behind this path is beginning to appear.
Sri Aurobindo compares the traditional practice of the Yoga of knowledge with the path of Hatha Yoga: “…but while the proper Yoga of knowledge is a philosophy of being put into spiritual practice, a psychological system, this is a science of being, a psycho-physical system. Both produce physical, psychic and spiritual results; but because they stand at different poles of the same truth, to one the psycho-physical results are of small importance, the pure psychic and spiritual alone matter, and even the pure psychic are only accessories of the spiritual which absorb all the attention; in the other the physical is of immense importance, the psychical a considerable fruit, the spiritual the highest and consummating result, but it seems for a long time a thing postponed and remote, so great and absorbing is the attention which the body demands. It must not be forgotten, however, that both do arrive at the same end. Hathayoga, also, is a path, though by a long, difficult and meticulous movement… to the Supreme.”
Sri Aurobindo, The Synthesis of Yoga, Part Two: The Yoga of Integral Knowledge, Chapter 27, Hathayoga, pp. 507-508