According to the Yoga Sutras of Patanjali, the ultimate aim of Yoga is to reach “Kaivalya” (emancipation or ultimate freedom). This is the experience of one’s innermost being or “soul” (the Purusa). Then one becomes free of chains of cause and effect (Karma) which tie us to continual reincarnation. In Kaivalya one is said to exist in peace and tranquillity, having attained absolute knowledge of the difference between the spiritual which is timeless, unchanging and free of sorrows, and the material which is not.
This is considered desirable as life is analysed as ultimately full of sorrows and pain- even pleasure and joy leave pain and loss when they have gone as nothing in the material world is permanent.
Yoga is therefore a spiritual quest. However, along the path of yoga, the aspirant also gains health, happiness, tranquillity and knowledge which are indicators of progress and an encouragement to continue their practice. Buddhism and other Eastern spiritual traditions use many techniques derived from Yoga.