"When there is duality, as it were, then one smells something, one sees something , one speaks something, one thinks something, one knows something. But, when to the knower of Brahman everything has become the Self, then what should one smell and through what, what should one hear and through what, what should one speak and through what, what should one think and through what, what should know and through what? That owing to which all this is known - through what, O Maitreyi, should one know the knower?"
The Brhadaranyaka Upanishad is considered by some to be the greatest Upanishad. Likewise, the commentary of Shankara is also regarded as his greatest. The theme is the all-embracing Brahman. The commentary shows how the great truth of the Brahman-Atman identity forms the main purport of all the Vedantic texts in general, and this Upanishad in particular. With Devanagari Sanskrit and English, translation and commentary.