śukla-kṛṣṇe gatī hy ete
jagataḥ śāśvate mate
ekayā yāty anāvṛttim
anyayāvartate punaḥ
śukla — light; kṛṣṇe — and darkness; gatī — ways of passing; hi — certainly; ete — these two; jagataḥ — of the material world; śāśvate — of the Vedas; mate — in the opinion; ekayā — by one; yāti — goes; anāvṛttim — to no return; anyayā — by the other; āvartate — comes back; punaḥ — again.
The same description of departure and return is quoted by Acarya Baladeva Vidyabhushana from the Chandogya Upanishad (5.10.3-5). Those who are fruitive laborers and philosophical speculators from time immemorial are constantly going and coming. Actually they do not attain ultimate salvation, for they do not surrender to Krishna.