Astanga Yoga - The Eight Limbs of Yoga
1. Yama (universal moral commandments)
2. Niyama (self purification by discipline)
3. Asana (posture)
4. Pranayama (rhythmic control of the breath)
5. Pratyahara- (withdrawal and emancipation of the mind from the domination of the senses and exterior objects)
6. Dharana (concentration)
7. Dhyana (meditation)
8. Samadhi (a state of super-consciousness brought about by pro-found meditation, in which the individual aspirant (sadhaka) becomes one with the object of his meditation—Paramatma or the Universal Spirit.)
Yama and Niyama control the yogi's passions and emotions and keep him in harmony with his fellow men. Asanas keep the body healthy and strong and in harmony with nature. Finally, the yogi becomes free of body consciousness. He conquers the body and renders it a fit vehicle for the soul. The first three stages are the outward quests (bahiranga sadhana).
The next two stages, Pranayama and Pratyahara, teach the aspirant to regulate the breathing, and thereby control the mind. This helps to free the senses from the thraldom of the objects of desire. These two stages of Yoga are known as the inner quests (antaranga sadhana).
Dharana, Dhyana and Samadhi take the yogi into the innermost recesses of his soul. The yogi does not look heavenward to find God. He knows that HE is within, being known as the Antaratma (the Inner Self). The last three stages keep him in harmony with himself
and his Maker. These stages are called antaratma sadhana, the quest of the soul.
By profound meditation, the knower, the knowledge and the known become one. The seer, the sight and the seen have no separate existence from each other. It is like a great musician becoming one with his instrument and the music that comes from it. Then, the yogi stands in his own nature and realises his self (Atman), the part of the Supreme Soul within himself.
The Yoga Sutra of Patanjali is divided into four chapters or pada. The first deals with samadhi, the second with the means (sadhana.) to achieve Yoga, the third enumerates the powers (vibhuti) that the yogi comes across in his quest, and the fourth deals with absolution (kaivalya).