Śivasaṃhitā 5.130

The image of nectar flowing ceaselessly from a triangular form at the crown reveals the subtle body as a living source of amṛta, immortality. This is not merely poetic: in Tantric physiology, sudhā — the lunar nectar — descends from the sahasrāra and is consumed by the digestive fire at the navel, causing aging and decay. Yogic practice seeks to reverse or conserve this vital flow.

Sudhā, a synonym of amṛta (literally «non-death»), names the substance of immortality itself. The qualifier trikoṇākāra — triangular in form — evokes the inverted triangle (trikona) associated with the feminine principle (śakti) and lunar energy. This triangle recurs in the iconography of the yoni and in the geometry of the śrīyantra, linking subtle anatomy to Tantric cosmology.

Practices such as viparītakaraṇī (the inverted posture) and khecarīmudrā are designed specifically to capture this nectar before it is consumed. The Haṭhapradīpikā dedicates significant passages to this physiology. Understanding this verse contextualizes why certain postures and mudrā-s carry explicit anti-aging purposes throughout classical Hatha Yoga literature.