Matsya Purana — Cosmography of Śākadvīpa and Successive Dvīpas: Mountains
प्रजापतिमुपादाय प्रजाभ्यो विदधत्स्वयम् तेषामन्तरविष्कम्भो द्विगुणः समुदाहृतः //
prajāpatimupādāya prajābhyo vidadhatsvayam teṣāmantaraviṣkambho dviguṇaḥ samudāhṛtaḥ //
Taking Prajāpati as the archetype, and himself laying down the rule for all beings, it is declared that their inner diameter (the clear internal span) is to be twice the base measure.
Rather than describing Pralaya, the verse uses Prajāpati (the creator-archetype) to authorize a normative rule: a fixed proportional standard for internal dimensions, reflecting cosmic order expressed through architecture.
For rulers and householders who commission halls, dwellings, or temples, it frames building as dharmic governance: construction should follow revealed proportional canons (here, the inner span is set as a ‘double’ measure), ensuring stability, auspiciousness, and social order.
It specifies a vastu-proportion: the antaraviṣkambha (clear internal diameter/span) should be dviguṇa—twice the relevant base unit previously defined—supporting correct layout for mandapas, sanctums, or measured spaces used for ritual and habitation.