Matsya Purana — Soma
तथाब्दमासाः पक्षाश्च शुक्लाः कृष्णास्तु वै स्मृताः पौर्णमास्यास्तु यो भेदो ग्रन्थयः संधयस्तथा //
tathābdamāsāḥ pakṣāśca śuklāḥ kṛṣṇāstu vai smṛtāḥ paurṇamāsyāstu yo bhedo granthayaḥ saṃdhayastathā //
Thus are the divisions of time remembered: years and months, and also the two fortnights (pakṣa), the bright (śukla, waxing) and the dark (kṛṣṇa, waning). The distinction connected with the full-moon observance (pūrṇamāsī) is likewise to be understood as the “knots” and “junctions,” the calendrical joints that mark transitions.
This verse is not about Pralaya; it focuses on kāla-vibhāga (time-reckoning), defining lunar divisions (bright/dark fortnights) and transitional ‘junctions’ used for ritual timing.
By clarifying months, fortnights, and full-moon distinctions, it supports correct observance of vows, śrāddha, donations, and state/household rites that must be performed on properly determined lunar dates.
Ritually, it highlights Paurṇamāsī (full-moon observance) and the importance of saṃdhi/granthi—transition points in the calendar—often treated as especially potent for vrata, homa, and other scheduled ceremonies.