What the term names
Patañjali defines āsana in two words: sthira-sukha-āsanam — the seat that is steady and at ease. The Yoga Sūtras spend exactly three of their 196 aphorisms on it (II.46–48) before moving on, which is a fair indication of the role the third limb was meant to play in the original eight-limb structure: a body that could be forgotten while the longer practice — prāṇāyāma, pratyāhāra, the three limbs of meditative absorption — did its work. The classical instruction is not a sequence of postures but a single sustained sitting in which the body has stopped registering as a problem. Everything else the term has accumulated in the modern reception is later.
The haṭha extension
The body-centred discipline most readers recognise as yoga in 2026 is a haṭha development from a much later layer of the tradition. The Haṭha Yoga Pradīpikā (15th century) and its companion texts catalogue around fifteen postures; the Gheraṇḍa Saṃhitā expands the list to thirty-two; the Śiva Saṃhitā lists eighty-four as the canonical full set. None of these texts present āsana as the centre of practice — the postures are propaedeutic to the prāṇāyāma, mudrā, bandha and samādhi work the texts treat as the actual yoga. The transformation into the studio practice the West inherited owes most to a single twentieth-century lineage: Tirumalai Krishnamacharya's reform at the Mysore palace in the 1930s and 1940s, which produced through three direct students — B.K.S. Iyengar, K. Pattabhi Jois and T.K.V. Desikachar — the three branches (Iyengar Yoga, Ashtanga Vinyāsa, Viniyoga) from which most contemporary postural yoga descends. The flow idiom in particular, with its vinyāsa sequencing of inhale-and-exhale-paired transitions, was substantially codified by Jois and is in this sense a thoroughly modern practice marketed under an ancient name. None of which makes the practice less useful — only worth knowing about, when the studio's claim to ancient continuity exceeds what the textual record supports.
Where to encounter it in the index
Sadhguru's *Inner Engineering: A Yogi's Guide to Joy* is the index's clearest sustained articulation of āsana in its older sense — the postural work is preparatory to the kriyā and meditative practices the Inner Engineering Online programme actually delivers, and the book repeatedly notes the modern conflation of yoga with āsana alone. Paramahansa Yogananda's *Autobiography of a Yogi* carries the older Bengal lineage's framing — āsana as the seat in which the kriya-yoga meditative work is conducted — though the book devotes very few pages to the postural side and many to its meditative descendants. Sadhguru's shorter talks repeatedly land on the same point: that āsana is a tool inside a longer instrument, and that its hypertrophy in the West has obscured the rest of the apparatus. Sadhguru on disability and spiritual practice is the index's clearest case for what āsana practice looks like when the body is not available in the form the studio assumes — and is by extension a clarifying piece on what the limb is actually for. Sadhguru on unlocking the mind's full potential sits in the same orientation, treating posture as instrumentally subordinate to attention. The MBSR tradition — Jon Kabat-Zinn's *Full Catastrophe Living* programme — carries a quieter descendant of the same instinct: the body scan and the gentle haṭha-derived stretching its eight-week curriculum prescribes are āsana under a clinical name, with the meditative work made the explicit aim and the postural work made instrumental to it. The hatha-yoga entry maps the textual genealogy in more detail; the patanjali entry maps the older one.
What it isn't
Āsana is not, on the classical reading, a fitness practice — its physiological benefits, real as they are, are side-effects rather than the aim. The Sūtras' three-aphorism treatment is unambiguous: the criterion of success is not flexibility, strength or aesthetic line but the disappearance of the body as a competing object of attention during the practice that follows. The studio class that turns the third limb into the entire practice is doing something the tradition does not endorse — not because the postures are wrong but because they are being asked to carry a load the tradition placed elsewhere. Āsana is also not, on either the classical or the haṭha reading, an aerobic discipline; the vinyāsa tempo of the contemporary flow class is a twentieth-century innovation responding to a fitness market the older texts did not anticipate. Reintroducing the longer apparatus — the pranayama, the pratyahara, the meditation limb the Sūtras place after — is what makes the practice yoga in the technical sense Patañjali used the word.
— end of entry —