। ॥ ५५ ॥
In plain words
Non-duality is happiness itself. Duality is suffering you cannot bear, and it never stops being that. Whichever of the two the real gain lies in — that is the one śruti teaches, and only that.
Close to the Sanskrit
Non-duality is of the nature of happiness; duality would always be unbearable suffering. Where the purpose would lie, that alone this śruti sets forth.