Yoga is one of the six orthodox systems of Indian philosophy. It was collated, co-ordinated and systematised by PataiijiHi in his classical work, the Yoga Sutras, which consists of 185 terse aphorisms. In Indian thought, everything is permeated by the Supreme Universal Spirit (Paramatma or God) of which the individual human spirit (j1vatma) is a part. The system of yoga is so called because it teaches the means by which the j1vatma can be united to, or be in communion with the Paramatma, and so secure liberation. One who follows the path of Yoga is a yogi or yogin. In the sixth chapter of the Bhagavad Gita, which is the most important authority on Yoga philosophy, Sri Krishna explains to Arjuna the meaning of Yoga as a deliverance from contact with pain and sorrow. As a well cut diamond has many facets, each reflecting a different colour of light, so does the word yoga, each facet reflecting a different shade of meaning and revealing different aspects of the entire range of human endeavour to win inner peace and happiness.