Matsya Purana — Solar–Lunar Motions
उत्तरं यदगस्त्यस्य शृङ्गं देवर्षिसेवितम् पितृयानः स्मृतः पन्था वैश्वानरपथाद्बहिः //
uttaraṃ yadagastyasya śṛṅgaṃ devarṣisevitam pitṛyānaḥ smṛtaḥ panthā vaiśvānarapathādbahiḥ //
That northern peak of Agastya, revered and frequented by the divine seers, is remembered as the Path of the Ancestors (Pitṛyāna), lying beyond the route called the Vaiśvānara-path.
This verse is not about Pralaya directly; it maps a cosmological route (Pitṛyāna) used to describe post-death movement in the ordered universe, implying a structured cosmos that persists across cycles.
By naming Pitṛyāna (the ancestral path), the verse implicitly supports the householder’s obligations to the Pitṛs—especially śrāddha and ancestral rites—since such duties are traditionally linked with the ancestral realm and its pathways.
Ritually, it highlights Pitṛyāna—reinforcing the importance of śrāddha/ancestor-offerings; architecturally, it has no direct Vāstu rule, but it belongs to the Purāṇic sacred-geography framework often used to sanctify pilgrimage and ritual orientation.