सूर्यरथ-कालचक्र-आयनविभागः, संध्योपासनम्, देवयान-पितृयानम्, विष्णुपद-गङ्गावतरणम्
आताम्रा हि भवन्त्य् आपो दिवा नक्तप्रवेशनात् दिनं विशति चैवाम्भो भास्करे ऽस्तम् उपागते तस्माच् छुक्लीभवन्त्य् आपो नक्तम् अह्नः प्रवेशनात्
ātāmrā hi bhavanty āpo divā naktapraveśanāt dinaṃ viśati caivāmbho bhāskare 'stam upāgate tasmāc chuklībhavanty āpo naktam ahnaḥ praveśanāt
दिवसा रात्रिचा अंश जलात प्रवेश करतो म्हणून पाणी तांबूस दिसते. आणि सूर्य अस्ताला गेल्यावर पाणी दिवसात प्रवेश करते. म्हणून रात्री दिवसाचा अंश प्रवेशल्याने पाणी शुभ्र व उजळ होते।
Sage Parāśara (teaching Maitreya)
It illustrates a Purāṇic cosmological principle: day and night are not merely external times but cyclical forces that “enter” and condition the world’s appearances, showing the universe as an ordered, law-governed system.
Parāśara frames day and night as alternating presences that successively ‘enter’ water and the world—by day, night is said to be entering (yielding a coppery tint), and after sunset, day is said to enter (yielding a brightened appearance).
Even when Vishnu is not named in the verse, the Vishnu Purana treats such cosmic regularity as grounded in the Supreme Reality—Vishnu as the sustaining principle whose sovereignty is reflected in the stable cycles of time and nature.