Matsya Purana — The Cave-Sanctuary: Jewel-Lake
तमसा चातिनिबिडं नल्वमात्रं सुसंकटम् नल्वमात्रमतिक्रम्य स्वप्रभाभरणोज्ज्वलम् //
tamasā cātinibiḍaṃ nalvamātraṃ susaṃkaṭam nalvamātramatikramya svaprabhābharaṇojjvalam //
There was a stretch of exceedingly dense darkness, perilous for the space of a nalva. Having crossed that nalva-long passage, one beheld a radiant expanse—brilliant with its own natural splendor, as though adorned with light itself.
It depicts a Pralaya-like threshold: a perilous belt of compact “tamas” (cosmic obscuration) that must be crossed before reaching a self-luminous state, suggesting transition from dissolution-darkness into a higher, radiant order.
Indirectly, it frames the ethical ideal of steadfastness: like crossing a dangerous dark stretch, a ruler or householder must endure संकट (crisis) with discipline to arrive at clarity—symbolically, dharma that leads beyond confusion.
No direct Vastu or ritual rule is stated; however, the imagery of moving from dense darkness into radiance is often echoed in ritual/temple symbolism (progress from outer obscurity to inner illumination), useful for interpretive context rather than technical prescription.