As the Sadhak (devotee or accomplisher) proceeds further, his ignorance vanishes. After the perfect attainment of Yoga, wisdom (Vivek) is awakened. So the purpose of Yoga is to achieve wisdom and to wipe off ignorance.
Now we come across the explanation of the eight aspects of Yoga as follows:
Yama means absence. Absence of violence, untruth, stealing intercourse and seizing is Yama!’ There are five aspects of Yama—they are non-violence, truth, not stealing, continence and not accumulating superfluous wealth. Never having animosity against any creature is non-violence.
The Niyam (the rules) are five, viz., (1) Shauch or purity, (2) Sant’osh or contentment, (3) Tap or penance, (4) Swadhyaya or continuous study of Vedas, (5) Ishwar Pranidhan or the concentration in God and offering everything to Him.
The stability and feeling comfort in a posture is Asan.
The control of breath while inhaling, (Purak), keeping it in the lungs for sometime (Kumbhak), and exhaling out (Rechak) are the three processes of Pranayam.
Pratyahar is controlling the mind by keeping away the organs of senses from external attractions to cut the relationship of the various sense-organs from their respective subject is Pratyahar.
To apply the mind to some internal subject is Dharana.
To concentrate attention on a particular subject of the mind is Dhyan.
Samadhi is attained when the attention becomes the objective. At this stage, the object of attention is not separate from the process of attention; instead, the process of attention is merged into the objective (Dhyeya). When Dhyar becomes stable in the Dhyeya (objective of attention), then there is Samadhi.