Posture is said to be the first limb of hatha yoga.

Posture comes first — and "first" here means foundational and preparatory. The verse continues by promising steadiness, health and lightness of limb, which is a modest and testable set of claims.

The whole first chapter then describes a small number of seated postures. The large modern pose vocabulary is a twentieth-century development, not a reading of this chapter.

Cited to suggest the text endorses posture practice as the main event. It calls posture the first limb, in a book whose subject is breath and inner practice.