The classical compilation attributed to Patanjali is frequently cited as the foundational text of yoga. Readers arriving from a modern studio usually find its contents unexpected.
Posture receives a few lines
The text addresses asana briefly, describing it as a seat that should be steady and comfortable, with no catalogue of positions and no sequences.
The instruction concerns a sitting position suitable for extended practice, which is consistent with the rest of the work's focus on sustained mental discipline.
The elaborate postural repertoire familiar today developed much later, in hatha yoga literature and then in twentieth-century systems, rather than from this text.
The subject is the activity of the mind
The work opens by defining yoga as the stilling of mental movements, and most of what follows concerns how that is approached and what obstructs it.
It catalogues kinds of mental activity, sources of difficulty, and stages of increasingly refined absorption, in language that is technical and compressed.
Read on its own terms, it is closer to a manual of contemplative psychology than to a guide to physical practice.
The eight limbs are not a syllabus of exercises
The well-known eight limbs begin with ethical restraints and observances, then posture, breath regulation, withdrawal of the senses, and three progressively deeper stages of concentration.
Five of the eight concern mental discipline and two concern conduct, which places posture as a single component within a much larger structure.
The sequence is often presented as a ladder, though commentators differ on whether the limbs are strictly successive or largely concurrent.
The text depends on its commentaries
Written in compressed aphorisms, the work is close to unreadable without explanation, and it has always circulated with commentary attached.
Different commentators read key terms differently, and several of the disagreements are substantial rather than verbal.
Modern translations therefore vary considerably, and a reader comparing two versions may find them making noticeably different claims.
Its prominence is partly a modern development
The text was not universally central in Indian tradition and had periods of relative neglect before renewed attention in the nineteenth and twentieth centuries.
Reformers and teachers presenting yoga to international audiences found in it a systematic and philosophical account that suited that purpose.
Its current status as the definitive source therefore reflects that history as much as continuous authority, which is worth knowing when it is cited as unchanging tradition.