These two paths of the bright and the dark are considered eternal of the world. By one one goes to not return; by the other one returns again.

The two gati (paths): śukla (white/bright, light) and kṛṣṇa (black/dark, darkness). They are śāśvate (eternal) — always operating in the conditioned world.

Ekayā — by the light one — yāti anāvṛttim — goes without return, to mokṣa. Anyayā — by the other — āvartate punaḥ — returns again to the cycle. Destiny depends on the moment of death and accumulated karma.