The Upanishads, Part 1 (SBE01), by Max Müller, , at sacred-texts.com
1. For that heart there are five gates belonging to the Devas (the senses). The eastern gate is the Prâna (up-breathing), that is the eye, that is Âditya (the sun). Let a man meditate on that as brightness (glory of countenance) and health. He who knows this, becomes bright and healthy.
2. The southern gate is the Vyâna (back-breathing), that is the ear, that is the moon. Let a man meditate on that as happiness and fame. He who knows this, becomes happy and famous.
3. The western gate is the Apâna (down-breathing), that is speech, that is Agni (fire). Let a man meditate on that as glory of countenance and health. He who knows this, becomes glorious and healthy.
4. The northern gate is the Samâna (on-breathing), that is mind, that is Parganya (rain). Let a man meditate on that as celebrity and beauty.
[paragraph continues] He who knows this, becomes celebrated and beautiful.
5. The upper gate is the Udâna (out-breathing), that is air, that is ether. Let a man meditate on that as strength and greatness. He who knows this, becomes strong and great.
6. These are the five men of Brahman, the doorkeepers of the Svarga (heaven) world. He who knows these five men of Brahman, the door-keepers of the Svarga world, in his family a strong son is born. He who thus knows these five men of Brahman, as the door-keepers of the Svarga world, enters himself the Svarga world.
7. Now that light which shines above this heaven, higher than all, higher than everything, in the highest world, beyond which there are no other worlds, that is the same light which is within man. And of this we have this visible proof 1:
8. Namely, when we thus perceive by touch the warmth here in the body 2. And of it we have this audible proof: Namely, when we thus, after stopping our ears, listen to what is like the rolling of a carriage, or the bellowing of an ox, or the sound of a burning fire 3 (within the ears). Let a man meditate on this as the (Brahman) which is seen and heard.
[paragraph continues] He, who knows this, becomes conspicuous and celebrated, yea, he becomes celebrated.
46:1 The meditation on the five gates and the five gate-keepers of the heart is meant to be subservient to the meditation on Brahman, as the ether in the heart, which, as it is said at the end, is actually seen and heard by the senses as being within the heart.
47:1 The presence of Brahman in the heart of man is not to rest on the testimony of revelation only, but is here to be established by the evidence of the senses. Childish as the argument may seem to us, it shows at all events how intently the old Brahmans thought on the problem of the evidence of the invisible.
47:2 That warmth must come from something, just as smoke comes from fire, and this something is supposed to be Brahman in the heart.
47:3 Cf. Ait. Âr. III, 2, 4, 11-13.