The entire Western yoga industry rests on two and a half sentences.
The Third Limb
Everything the modern West means by "yoga" — the studios, the mats, the sequences, the athleisure economy — descends from a limb Patanjali dispatches in three sutras. Sthira sukham asanam (II.46): the posture should be steady and comfortable. It is mastered when effort relaxes and the mind merges into the infinite (II.47), and then the practitioner is no longer assaulted by the pairs of opposites — heat and cold, pleasure and pain (II.48). That is the whole treatment. The word asana comes from the root as, to sit; in the Sutras it means, quite literally, the seat.
Patanjali is not teaching downward dog. He is solving an engineering problem: the limbs that follow require sitting motionless for a long time, and a body that aches, fidgets, or slumps will keep dragging attention back to itself. Asana is the art of making the body disappear from awareness — steady enough to be forgotten, comfortable enough to be sustained.
Practice
The elaborate postural systems came later, largely through Hatha yoga — texts like the Hatha Yoga Pradipika (15th century) that developed physical culture as preparation for the subtle-body work of breath and energy. Modern postural yoga is younger still, substantially a 20th-century synthesis. None of this makes the physical practice false; it makes it preparatory, which is what the tradition always said it was. A body that has been stretched, strengthened, and settled sits better than one that has not. The confusion is only in mistaking the doorstep for the house.
The classical instruction is minimal: take a seat that lets the spine be upright and the body at ease, then release effort until sitting sustains itself. The posture becomes steady not by force but by the relaxation of everything unnecessary — a physical rehearsal for what the later limbs do with the mind. Whatever settles awareness into the body this way serves the same end, which is why Meditation traditions the world over converge on the same upright, effortless seat.
Place in the Sequence
Asana stands between ethics and energy. With conduct ordered by Yama and Niyama, the practitioner turns to the instrument itself — first the gross body here, then the breath in Pranayama, the fourth limb. The sequence moves steadily inward, from the world, to the body, to the breath, to the senses, to the mind. Asana is the last limb visible from the outside.
Related
- Eight Limbs of Yoga — the sequence
- Niyama — the previous limb, inner observance
- Pranayama — the next limb, the breath
- Yoga — the parent overview
- Meditation — what the seat is for