Little is known of Patanjali the person; the Yoga Sutras attributed to him are undated and compressed to the point of aphorism. The text systematized yoga into eight limbs (ashtanga), from ethical foundation through meditative absorption (Samadhi), and gave the tradition its most concise philosophical statement.
His first definition of yoga has not been improved on: yogash chitta vritti nirodhah — yoga is the cessation of the modifications of the mind.