Matsya Purana — Soma
गतागतज्ञः प्रेतानां प्राप्तिं श्राद्धस्य चैव हि कृष्णपक्षस्त्वहस्तेषां शुक्लः स्वप्नाय शर्वरी //
gatāgatajñaḥ pretānāṃ prāptiṃ śrāddhasya caiva hi kṛṣṇapakṣastvahasteṣāṃ śuklaḥ svapnāya śarvarī //
The knower of the departed spirits’ coming and going understands indeed how the śrāddha offering reaches them. For those beings, the dark fortnight (kṛṣṇa-pakṣa) is their “day,” while the bright fortnight (śukla-pakṣa) is their “night,” meant for dreaming.
This verse is not about cosmic pralaya; it explains the subtle, ritual cosmology of time for pretas—how lunar fortnights are experienced as their day and night in the context of śrāddha.
It supports the householder’s (and thus the king’s) duty to maintain dharma through properly timed śrāddha, emphasizing that offerings reach the departed according to specific lunar timings recognized in Purāṇic ritual science.
The significance is ritual (not architectural): it links śrāddha efficacy to lunar cycles, teaching that the kṛṣṇa-pakṣa and śukla-pakṣa function as the preta’s day and night, guiding when rites and related observances are most appropriate.