Matsya Purana — Measures of Time: Caturyuga Computation
मानुषेणैव मानेन वर्षाणां यच्छतं भवेत् पितॄणां तानि वर्षाणि संख्यातानि तु त्रीणि वै दश च द्व्यधिका मासाः पितृसंख्येह कीर्तिता //
mānuṣeṇaiva mānena varṣāṇāṃ yacchataṃ bhavet pitṝṇāṃ tāni varṣāṇi saṃkhyātāni tu trīṇi vai daśa ca dvyadhikā māsāḥ pitṛsaṃkhyeha kīrtitā //
By the human measure, whatever amounts to one hundred years becomes, in the reckoning of the Pitṛs, their years; and in this Pitṛ-calculation it is declared to be three years with ten months added—thus is the ancestral count stated here.
It does not describe Pralaya directly; it gives a technical kāla-māna (time-reckoning) teaching, explaining how human years are converted into the Pitṛs’ (ancestral) measure of time used in cosmology and ritual contexts.
By defining Pitṛ-reckoning, it supports correct observance of śrāddha and ancestor rites—key household and royal obligations in the Matsya Purana’s dharma framework, where timing and calendrical accuracy are treated as part of ritual duty.
The significance is ritual rather than architectural: it provides the ancestral time-scale used when discussing śrāddha, Pitṛ offerings, and related calendrical computations that depend on differing cosmic “clocks.”