The other attendant āsanas preceded by the four fundamental āsanas have a common point showing more relaxed mode than the latter. The other attendant āsanas are distinguished mainly by a mode of folding or stretching legs. The steadiness leads the comfortableness properly among fundamental āsanas, while the comfortableness leads the steadiness properly among the other attendant āsanas. The steadiness required in āsanas is to aim at concentrated meditation after all, and it needs the comfortableness for this aim. Patañjali says in Yogasūtra(Ⅱ.47), “[Āsana are perfected] by relaxation of effort and by attaining oneness in meditation with the infinite.” This instruction is to elucidate the principle of āsanas again. In this case, we can understand that ‘relaxation of effort’ means the comfortableness, and that ‘attaining oneness in meditation with the infinite’ means the steadiness. As explained in Yogasūtra-bhāṣya, just a āsana that leads to mental concentration by relaxation of effort is a perfected āsana intended in classical yoga. Just here is a turning point where āsanas are divided into Rāja-yoga and Haṭha-yoga. Peculiar āsanas of Haṭha-yoga substitute stiffness for steadiness i.e. effort, and relaxation for comfortableness. However repeated training of both stiffness and relaxation is effective in order to maintain āsanas of classical yoga requiring steadiness and comfortableness. Therefore from this point of view, when āsanas of Haṭha-yoga become the process of matching steadiness and comfortableness, they are recognized as valuable means for classical yoga.
