This is the Self
This universe comes forth from Brahman, exists in Brahman, and will return to Brahman. Verily all is Brahman.
A man is what his deep desire is. It is his deep desire in this life that shapes he life to come. So let him direct his deep desire to realize the Self.
The Self, who can be realized by the pure in heart, who is life, light, truth, space, who gives rise to all works, all desires, all odors, all tastes, who is beyond words, who is joy abiding -- this is the Self dwelling in my heart.
Smaller than a grain of rice, smaller than a grain of barley, smaller than a mustard seed, smaller than a grain of millet, smaller even that the kernel of a grain of millet is the Self. This is the Self dwelling in my heart, greater than the earth, greater than the sky, greater than all the worlds.
This Self who gives rise to all works, all desires, all odors, all tastes who pervade the universe, who is beyond words, who is joy abiding, who is ever present in my heart, is Brahman indeed. To him I shall attain when my ego dies.
Chandogya Upanishad











