DEATH IS THE ULTIMATE UNION OF SELF AND ALL BY UNKNOWN

When a person is dying, his voice goes into his mind; his mind into his breath; his breath into heat; the heat into the highest divinity. that which is the finest essence - the whole world has that as its soul. That is Reality. That is Atman. That art thou, Svetaketu. [Chanodgya 6.8.6]

As these flowing rivers that tend towards the ocean, on reaching the ocean disappear, their name and form are destroyed and it is called simply "the ocean" - even so of this spectator these sixteen parts that tend towards the Person [Purusha, the cosmic unity], on reaching the Person disappear, their name and form are destroyed, and it is called simply "the Person." [Prasna 6.5]

When one has come into the presence of undecaying immortals, What decaying mortal here below, who understands, who meditates on the pleasures of beauty and delight, Would delight in a life over-long? [Katha 1.28] When are cut all the knots of the heart here on earth, then a mortal becomes immortal! [Katha 6.15]