Adhyāya 39 — त्रिगुणविवेकः (Discrimination of the Three Guṇas) and Avyakta-Doctrine
अहस्त्रिधा तु विज्ञेयं त्रिधा रात्रिविधीयते । मासार्धमासवर्षाणि ऋतव: संधयस्तथा,गुणोंके भेदसे दिनको भी तीन प्रकारका समझना चाहिये। रात भी तीन प्रकारकी होती है तथा मास, पक्ष, वर्ष, ऋतु और संध्याके भी तीन-तीन भेद होते हैं
ahastridhā tu vijñeyaṃ tridhā rātrir vidhīyate | māsārdhamāsavarṣāṇi ṛtavaḥ sandhayas tathā ||
Vāyu said: “Time should be understood as having threefold divisions: the day is to be known in three ways, and the night too is arranged in three ways. Likewise, the month, the half-month (fortnight), the year, the seasons, and the junctions (twilights) are each spoken of as having threefold distinctions.”
वायुदेव उवाच