He who knows at the same time both the Unmanifested (the cause of manifestation) and the destructible or manifested, he crosses over death through knowledge of the destructible and attains immortality through knowledge of the First Cause (Unmanifested).
This particular Upanishad deals chiefly with the Invisible Cause and the visible manifestation, and the whole trend of its teaching is to show that they are one and the same, one being the outcome of the other hence no perfect knowledge is possible without simultaneous comprehension of both. The wise men declare that he who worships in a one-sided way, whether the visible or the invisible, does not reach the highest goal. Only he who has a co-ordinated understanding of both the visible and the invisible, of matter and spirit, of activity and that which is behind activity, conquers Nature and thus overcomes death. By work, by making the mind steady and by following the prescribed rules given in the Scriptures, a man gains wisdom. By the light of that wisdom he is able to perceive the Invisible Cause in all visible forms. Therefore the wise man sees Him in every manifested form. They who have a true conception of God are never separated from Him. They exist in Him and He in them.