B.K.S. Iyengar put light on the Patanjali’s Yoga sutras - the bible of yoga and made it more accessible to the yoga practitioners around the world.
Patanjali was a great sage who lived somewhere between 500 B.C. and 200 B.C. He encoded the science of yoga in the form of 4 chapters consisting 196 sutra-s or aphorisms which are known as Yoga Sutras.
Yoga contains eight limbs or aspects. It is called Ashtanga Yoga.
Asht means eight, anga means limbs or aspects, which are:
Yama: social discipline
Niyama: individual discipline
Asana: control of the body in various postures
Pranayama: control of breath
Pratyahara: control of the senses and mind
Dharana: concentration
Dhyana: meditation
Samadhi: liberation, absorption
The first four stages of Patanjali's ashtanga yoga concentrate on refining our personalities, gaining mastery over the body, and developing an energetic awareness of ourselves, all of which prepares us for the second half of this journey, which deals with the senses, the mind, and attaining a higher state of consciousness.