This very multitude of beings, having come into existence again and again, dissolves Helplessly at the coming of the night, O son of Pritha (Pārtha), and comes forth at the coming of the day.
Arjuna, the throng of creatures that comes to exist dissolves unwillingly at nightfall to emerge again at daybreak.
(19) Yes, this whole host of beings comes ever anew to be; at fall of night it dissolves away all helpless; at dawn of day it rises up again.
8.19 O son of Pṛthā, after being born again and again, that very multitude of beings disappears in spite of itself at the approach of night. It comes to life at the approach of day.
8.19
8.19 This same multitude of beings, being born again and again, is dissolved, helplessly, O Arjuna (into the Unmanifested) at the coming of the night and comes forth at the coming of the day.