SOURCE This trans. is in ‘The Upanishads, Breath of the Eternal’, by Swami Prabhavananda.

“Like two birds of golden plumage, inseparable companions, the individual self and the immortal Self are perched on the branches of the self same tree. The former tastes of the sweet and bitter fruits of the tree; the latter, tasting of neither, calmly observes.

“The individual self, deluded by forgetfulness of his identity with the divine Self, bewildered by his ego, grieves and is sad. But when he recognizes the worshipful Lord as his own true Self, and beholds his glory, he grieves no more.”