Now, indeed, O king, this is the Brahma-knowledge, even the knowledge contained in all the Upanishads, as declared to us by the honorable Maitri. I will narrate it to you. Now, the Valakhilyas are reputed as free from evil, of resplendent glory, living in chastity. Now, they said to Kratu Prajapati: “Sir, this body is like a cart without intelligence (acetana). To what supersensuous being, forsooth, belongs such power whereby this sort of thing is set up in the possession of this sort of intelligence? Or, in other words, who is its driver? Sir, tell us what you know!” Then he said to them: “He, assuredly, indeed, who is reputed as standing aloof, like those who, among qualities, abstain from intercourse with them. He, verily, is pure, clean, void, tranquil, breathless, selfless, endless, undecaying, steadfast, eternal, unborn, independent. He abides in his own greatness. By him this body is set up in possession of intelligence; or, in other words, this very one, verily, is its driver.” Then they said: “Sir, how by this kind of indifferent being is this sort of thing set up in possession of intelligence? Or, in other words, how is this one its driver?” Then he said to them: “Verily, that subtle, ungraspable, invisible one, called the Person, turns in here [in the body] with a part [of himself] without there being any previous awareness, even as the awakening of a sleeper takes place without there being any previous awareness. Now, assuredly, indeed, that part of Him is what the intelligence-mass here in every person is the spirit (knower-of-the-body) which has the marks of conception, determination, and self-conceit, Prajapati (Lord of Creation), under the name of individuality.
The Maitri Upanishad (also known as the Maitrayaniya Upanishad) is one of the ancient scriptures, written in Sanskrit and held sacred to Hinduism and Buddhism. It consists of seven lessons, many of which discuss metaphysical questions about the soul (Atman), concluding that man is the ultimate self – the immortal Brahman. In particular, the Maitri Upanishad asks how joy is possible in an existence pervaded by suffering and whether a soul can achieve freedom in this life. It also allows for deity worship but sees such practices as temporary, which eventually must be relinquished to find true enlightenment through meditation and self-knowledge.