This Upanishad holds a pre-eminent position in the age-old spiritual tradition of India. It forms the last chapter of the Shukla Yajur Veda Samhita. The message of this small Upanishad, having only eighteen verses, is as profound as it is all-comprehensive. It proclaims the divinity of man and nature and the spiritual oneness of all existence. It asserts that God is enveloping everything, nay more, God is in everything. It can be said that this Upanishad provides the fundamental theme of Vedantic thought.The book contains the original Upanishad and the English translation of Shankaracharya’s commentary on it.