The Yoga Sutra begins with this aphorism: Yogah chitta vrittih nirodha: Yoga is restraining the mind from discursive thought. This restraint, it believes, can be brought about by discipline, both physical and mental. In the sutra, discipline is outlined as an eightfold path, starting from yama (self-restraint), niyama (virtuous observances), asana (posture), pranayama (consciously controlling breath), pratyahara (withdrawal of the senses), dharana (concentrating the mind), dhyana (meditation), and samadhi (a trance-like state in which there is complete union with the subject of meditation).
