सूर्यरथनिर्णयः (चन्द्रस्य पक्षवृद्धिक्षयविधानम्)
यावत्तु क्षीयते तस्य भागः पञ्चदशस्तु सः अमावास्यां ततस्तस्या अन्तरा पूर्यते पुनः
yāvattu kṣīyate tasya bhāgaḥ pañcadaśastu saḥ amāvāsyāṃ tatastasyā antarā pūryate punaḥ
それの減じてゆく分は第十五分と数えられる。アマーヴァーシャー(新月)においてそれはその分だけ減り、のちにその間の期間で再び満ちてゆく(再び増大する)。
Suta Goswami
It links Shiva-puja to sacred time (kāla) by describing the Moon’s waning and waxing that define tithis; observing amāvāsyā and the lunar cycle helps time vrata, abhiṣeka, and dāna in a ritually precise way.
By emphasizing cyclical decrease and replenishment, it points to kāla as a regulated power within creation—while Shiva as Pati is the transcendent lord of kāla, the Pashu experiences change and rhythm through such cosmic measures.
Tithi-based observance—especially amāvāsyā-related rites (vrata, śrāddha, japa, and Shiva-abhiṣeka)—supporting Pashupata discipline through regularity and mastery over time-bound impulses (pāśa).