Matsya Purana — Measures of Time: Caturyuga Computation
दिव्येन च प्रमाणेन प्रवक्ष्याम्यन्तरं मनोः सहस्राणां शतान्याहुः स च वै परिसंख्यया //
divyena ca pramāṇena pravakṣyāmyantaraṃ manoḥ sahasrāṇāṃ śatānyāhuḥ sa ca vai parisaṃkhyayā //
And now, by the divine measure of time, I shall explain the interval of a Manu. It is declared to be hundreds of thousands, and that too by precise calculation.
It frames cosmic history in measurable, “divine” units, implying that events like pralaya and renewal occur according to fixed, computable cycles rather than randomness.
Indirectly, it grounds dharma in long cosmic order: a king or householder is encouraged to act with restraint and perspective, knowing human life sits within vast, regulated Manvantara cycles.
No direct Vāstu or ritual rule is stated; the takeaway is methodological—ritual calendars and traditional reckonings rely on standardized “divine” measures of time used in Purāṇic computation.