Matsya Purana — Description of Gomedaka and Puṣkara Dvīpas; the Lokāloka Boundary; Ocean Tide...
परस्पराधिकाश्चैव प्रविष्टाश्च परस्परम् एवं परस्परोत्पन्ना धार्यन्ते च परस्परम् //
parasparādhikāścaiva praviṣṭāśca parasparam evaṃ parasparotpannā dhāryante ca parasparam //
Each is superior to the other in its own manner, and they enter into one another. Thus, arising mutually from one another, they also sustain one another.
It presents a cosmological principle: manifested realities arise through reciprocal causation and remain stable through mutual support—an idea used in Purāṇic creation accounts and reversed in dissolution when this interdependence withdraws.
By analogy, it supports the dharmic view that society and household life function through interdependence—king and subjects, patron and priest, family members and guests—each sustaining the other through rightful roles.
While not naming Vāstu rules directly, the principle aligns with Vāstu-śāstra and ritual logic: parts of a temple/ritual system must be proportioned and integrated so that each component ‘enters’ and supports the whole.