Matsya Purana — Measures of Time: Caturyuga Computation
*ऋषय ऊचुः चतुर्युगाणि यानि स्युः पूर्वे स्वायम्भुवे ऽन्तरे एषां निसर्गसंख्यां च श्रोतुमिच्छाम विस्तरात् //
*ṛṣaya ūcuḥ caturyugāṇi yāni syuḥ pūrve svāyambhuve 'ntare eṣāṃ nisargasaṃkhyāṃ ca śrotumicchāma vistarāt //
The sages said: “We wish to hear in detail the number and sequence, by the natural reckoning, of the caturyugas that occur in the earlier Svāyambhuva Manvantara.”
It frames the Purāṇic model of cyclic time—manvantaras containing repeated caturyugas—providing the chronological backdrop typically used to explain creation, re-creation, and periodic dissolutions.
Indirectly, it grounds dharma in cosmic order: royal and household duties are often taught as appropriate to the yuga and manvantara context, so knowing the time-cycle helps interpret when and why particular dharmic rules are emphasized.
No direct Vāstu or ritual procedure is stated; the verse is a chronological inquiry. In the Matsya Purāṇa, such time-reckoning often serves as the framework before prescribing rites, donations, or temple-building merits for particular ages.