Ashtanga (eight limbs of yoga)
Ashtanga, the eight limbs of yoga, is Patanjali's classification of classical yoga, as set out in his Yoga Sutras. He defined the eight limbs as yama (abstinences), niyama (observances), asana (postures), pranayama (breathing), pratyahara (withdrawal), dharana (concentration), dhyana (meditation) and samadhi (absorption).
The eight limbs form a sequence from the outer to the inner. Postures, important in modern yoga, form one limb of Patanjali's scheme; he states only that they must be steady and comfortable.
The eight limbs of yoga are yama (abstinences), niyama (observances), asana (yoga postures), pranayama (breath control), pratyahara (withdrawal of the senses), dharana (concentration), dhyana (meditation) and samadhi (absorption)."
The eightfold path of Patanjali's yoga consists of a set of prescriptions for a morally disciplined and purposeful life, of which asanas (yoga postures) form only one limb.
Patanjali, in Book 2, states how and why each of the above self-restraints help in an individual's personal growth. For example, in verse II.35, Patanjali states that the virtue of nonviolence and non-injury to others (Ahimsa) leads to the abandonment of enmity, a state that leads the yogi to the perfection of inner and outer amity with everyone, everything.
As with the Yamas, Patanjali explains how and why each of the Niyamas help in personal growth. For example, in verse II.42, Patanjali states that the virtue of contentment and acceptance of others as they are (Santosha) leads to the state where inner sources of joy matter most, and the craving for external sources of pleasure ceases.
Asana is a posture that one can hold for a period of time, staying relaxed, steady, comfortable and motionless. The Yoga Sutra does not list any specific asana. Āraṇya translates verse II.47 of Yoga sutra as, "asanas are perfected over time by relaxation of effort with meditation on the infinite"; this combination and practice stops the quivering of body. Any posture that causes pain or restlessness is not a yogic posture. Secondary texts that discuss Patanjali's sutra state that one requirement of correct posture for sitting meditation is to keep chest, neck and head erect (proper spinal posture).
The Bhasya commentary attached to the Sutras, now thought to be by Patanjali himself, suggests twelve seated meditation postures: Padmasana (lotus), Virasana (hero), Bhadrasana (glorious), Svastikasana (lucky mark), Dandasana (staff), Sopasrayasana (supported), Paryankasana (bedstead), Krauncha-nishadasana (seated heron), Hastanishadasana (seated elephant), Ushtranishadasana (seated camel), Samasansthanasana (evenly balanced) and Sthirasukhasana (any motionless posture that is in accordance with one's pleasure).
Over a thousand years later, the Hatha Yoga Pradipika mentions 84 [a] asanas taught by Shiva, stating four of these as most important: Siddhasana (accomplished), Padmasana (lotus), Simhasana (lion), and Bhadrasana (glorious), and describes the technique of these four and eleven other asanas. In modern yoga, asanas are prominent and numerous, unlike in any earlier form of yoga.
After a desired posture has been achieved, verses II.49 through II.51 recommend prāṇāyāma, the practice of consciously regulating the breath (inhalation, the full pause, exhalation, and the empty pause). This is done in several ways, such as by inhaling and then suspending exhalation for a period, exhaling and then suspending inhalation for a period, by slowing the inhalation and exhalation, or by consciously changing the timing and length of the breath (deep, short breathing).
Pratyāhāra is a combination of two Sanskrit words prati- (the prefix प्रति-, "against" or "contra") and āhāra (आहार, "bring near, fetch").
Pratyahara is drawing within one's awareness. It is a process of retracting the sensory experience from external objects. It is a step of self extraction and abstraction. Pratyahara is not consciously closing one's eyes to the sensory world, it is consciously closing one's mind processes to the sensory world. Pratyahara empowers one to stop being controlled by the external world, fetch one's attention to seek self-knowledge and experience the freedom innate in one's inner world.
Pratyahara marks the transition of yoga experience from the first four limbs of Patanjali's Ashtanga scheme that perfect external forms, to the last three limbs that perfect the yogin's inner state: moving from outside to inside, from the outer sphere of the body to the inner sphere of the spirit.
Dharana (Sanskrit: धारणा) means concentration, introspective focus and one-pointedness of mind. The root of the word is dhṛ (धृ), meaning "to hold, maintain, keep".
Dharana, as the sixth limb of yoga, is holding one's mind onto a particular inner state, subject or topic of one's mind. The mind is fixed on a mantra, or one's breath/navel/tip of tongue/any place, or an object one wants to observe, or a concept/idea in one's mind. Fixing the mind means one-pointed focus, without drifting of mind, and without jumping from one topic to another.
Dhyana (Sanskrit: ध्यान) literally means "contemplation, reflection" and "profound, abstract meditation".
Dhyana is contemplating, reflecting on whatever Dharana has focused on. If in the sixth limb of yoga one focused on a personal deity, Dhyana is its contemplation. If the concentration was on one object, Dhyana is non-judgmental, non-presumptuous observation of that object. If the focus was on a concept/idea, Dhyana is contemplating that concept/idea in all its aspects, forms and consequences. Dhyana is uninterrupted train of thought, current of cognition, flow of awareness.
Dhyana is integrally related to Dharana, one leads to other. Dharana is a state of mind, Dhyana the process of mind. Dhyana is distinct from Dharana in that the meditator becomes actively engaged with its focus. Patanjali defines contemplation (Dhyana) as the mind process, where the mind is fixed on something, and then there is "a course of uniform modification of knowledge". Adi Shankara, in his commentary on Yoga Sutras, distinguishes Dhyana from Dharana, by explaining Dhyana as the yoga state when there is only the "stream of continuous thought about the object, uninterrupted by other thoughts of different kind for the same object"; Dharana, states Shankara, is focussed on one object, but aware of its many aspects and ideas about the same object. Shankara gives the example of a yogin in a state of dharana on morning sun may be aware of its brilliance, color and orbit; the yogin in dhyana state contemplates on sun's orbit alone for example, without being interrupted by its color, brilliance or other related ideas.
Samadhi is oneness with the subject of meditation. There is no distinction, during the eighth limb of yoga, between the actor of meditation, the act of meditation and the subject of meditation. Samadhi is that spiritual state when one's mind is so absorbed in whatever it is contemplating on, that the mind loses the sense of its own identity. The thinker, the thought process and the thought fuse with the subject of thought. There is only oneness, samadhi.