Yoga comes out of an oral tradition in which the teaching was transmitted directly from teacher to student. The Indian sage Patanjali has been credited with the collation of this oral tradition into his classic work, the Yoga Sutra, a 2,000-year-old treatise on yogic philosophy. A collection of 195 statements, the Sutra provides a kind of philosophical guidebook for dealing with the challenges of being human. Giving guidance on how to gain mastery over the mind and emotions and advice on spiritual growth, the Yoga Sutra provides the framework upon which all yoga practiced today is based. "Sutra," literally meaning "thread," has also been translated as "aphorism," a tersely phrased statement of truth. Another definition of "sutra" is "the condensation of the greatest amount of knowledge into the most concise description possible." Keeping these meanings in the mind, we might think of the art and science of yoga as a kind of magnificent tapestry that is woven together by the threads of universal truths.
Initially, the discipline of hatha yoga—the physical aspect of yoga—was developed as a vehicle for meditation. The repertoire of hatha yoga prepared the body, and particularly the nervous system, for stillness, creating physical strength and stamina that allowed the mind to remain calm.