Brihadaranyaka-Upanishad: Third Adhyâya, Fourth Brahmana

1. Then Ushasta Kakrayana asked. “Yagnavalkya,” he said, “tell me the Brahman which is visible, not invisible, the Self (atman), who is within all.”

Yagnavalkya replied: “This, thy Self, who is within all.”

“Which Self, O Yagnavalkya, is within all?”

Yagnavalkya replied: “He who breathes in the up-breathing, he is thy Self, and within all. He who breathes in the down-breathing, he is thy Self, and within all. He who breathes in the on-breathing, he is thy Self, and within all. He who breathes in the out-breathing, he is thy Self, and within all. This is thy Self, who is within all.”

2. Ushasta Kakrayana said: “As one might say, this is a cow, this is a horse, thus has this been explained by thee. Tell me the Brahman which is visible, not invisible, the Self, who is within all.”

Yagnavalkya replied: “This, thy Self, who is within all.”

“Which Self, O Yagnavalkya, is within all?”

Yagnavalkya replied: “Thou couldst not see the (true) seer of sight, thou couldst not hear the (true) hearer of hearing, nor perceive the perceiver of perception, nor know the knower of knowledge. This is thy Self, who is within all. Everything also is of evil.” After that Ushasta Kakrayana held his peace.