भूतग्रामः स एवायं भूत्वा भूत्वा प्रलीयते। रात्र्यागमेऽवशः पार्थ प्रभवत्यहरागमे ॥

bhūta-grāmaḥ sa evāyaṁ bhūtvā bhūtvā pralīyate rātryāgame ’vaśhaḥ pārtha prabhavatyahar-āgame

This multitude of beings, going forth repeatedly, is dissolved at the coming of night: by ordination, O Pârtha, it streams forth at the coming of day.

In plain words: All living beings come into existence again and again. They dissolve when the cosmic night comes and appear again when the day comes. This happens by a fixed law, not by their own choice.