Matsya Purana — Ritual Procedure and Merit of Donating the Ratnācala
मध्यमः पञ्चशतिकस् त्रिशतेनाधमः स्मृतः चतुर्थांशेन विष्कम्भपर्वताः स्युः समन्ततः //
madhyamaḥ pañcaśatikas triśatenādhamaḥ smṛtaḥ caturthāṃśena viṣkambhaparvatāḥ syuḥ samantataḥ //
The ‘middling’ measure is said to be five hundred (yojanas), and the ‘lower’ measure is remembered as three hundred. On every side, the Viṣkambha mountains are to be measured by one-fourth of the relevant standard.
This verse is not about Pralaya; it belongs to a cosmographic/measurement section, defining traditional size-classes and proportional standards for mountains.
Indirectly, it supports the Purāṇic ideal of orderly knowledge—standard measures and classifications that underpin dharmic governance (mapping realms, describing sacred lands) and ritual geography.
The key idea is proportional measurement—especially the ‘one-fourth’ rule—mirroring Vāstu practice where quarter-based ratios guide layout, extent, and symmetry in sacred planning.