Chandogya Upanishad 6.10.1

6.10.1

imāḥ somya nadyaḥ purastāt prācyaḥ syandante paścāt pratīcyaḥ \
tāḥ samudrāt samudram evāpiyanti \
sa samudra eva bhavati \
tā yathā tatra na vidur iyam aham asmīyam aham asmīti \\610.1\

'These eastern rivers, dear boy, flow along to the east and the western ones to the west. They rise from the ocean and merge in the ocean, and become that ocean itself. And there as these rivers do not know themselves as "I am this river, I am that river", even so, dear boy, all these creatures, having come from Being, do not know, "We have come from Being". And whatever these creatures were here, tiger or lion or wolf or boar or worm or fly or gad-fly or mosquito, that they become again.