Yuga-Vibhāga and Kāla-Pramāṇa
Measures of Time and the Four Yugas
अहोरात्रौ विभजते सूर्यो मानुषलौकिकौ
ahorātrau vibhajate sūryo mānuṣalaukikau
The Sun divides, for humankind, the worldly day and the worldly night.