Brahma Knowledge, by L. D. Barnett, , at sacred-texts.com
"Verily this All is Brahma. It has therein its birth, end, breath; as such one should worship it in stillness.
Verily man is made of will. As is man's will
in this world, such he becomes on going hence; so let him frame the will.
Made of mind, bodied in breath, shaped in light, real of purpose, ethereal of soul, all-working, all-desiring, all-smelling, all-tasting, grasping this All, speaking naught, heeding naught—this is my Self within my heart, smaller than a rice-corn, or a barley-corn, or a mustard-seed, or a canary-seed, or the pulp of a canary-seed—this is my Self within my heart, greater than earth, greater than sky, greater than heaven, greater than these worlds. All-working, all-desiring, all-smelling, all-tasting, grasping this All, speaking naught, heeding naught—this is my Self within my heart, this is Brahma; to Him shall I win when I go hence. He with whom it is thus has indeed no doubt." Thus spake Śāṇḍilya.
63:1 They pass every day into dreamless sleep, the perfect union with Brahma in the heart; but they are not conscious of this union, and the condition of their existence causes it to be only temporary. See above, § 15.
63:2 Chhāndogya Upanishad, iii. 14.