नारद-देवमत-संवादः
Nārada–Devamata Dialogue on Prāṇa, Apāna, and Udāna
प्राणापानाविदं द्वन्द्भवाक् चोर्ध्व॑ च गच्छत: । व्यान: समानश्वैवोभौ तिर्यग् द्वन्द्धत्वमुच्यते,प्राण और अपान--ये दोनों भी द्वन्द्ध हैं। ये नीचे और ऊपरको जाते हैं। व्यान और समान--ये दोनों मध्यगामी द्वन्द्ध कहे जाते हैं
prāṇāpānāv idaṃ dvandvabhāvāc cordhvaṃ ca gacchataḥ | vyānaḥ samānaś caivobhau tiryag dvandvatvam ucyate ||
Nārada said: Prāṇa and Apāna form a paired opposition: they move in opposite directions—one upward and the other downward. Likewise, Vyāna and Samāna are also spoken of as a duality, moving laterally and pervading the middle. Thus the vital functions within the body are understood through complementary pairs, revealing an ordered balance.
नारद उवाच