third Prashna uses symbolic phrases, relying on more ancient texts. It states, in verse 3.5 for example, that "seven lights" depend on air circulated by arteries in order to function, which is a phrase which means "two eyes, two ears, two nostrils and mouth". Its answers to metaphysical questions are physiological, rather than philosophical. What establishes man? - Fourth Prashna The first three Prashnas of the Upanishad focus on cause and effect of the transient, empirical, manifested world, remarks Eduard Roer. The fourth through sixth Prasna of the Upanishad focus on the nature of Self, that which is unchanging and independent of cause, of proof, and is self-evident. The fourth Prashna lists five questions: (1) What sleeps in man? (2) What is awake therein (when he sleeps)? (3) Which Deva (god, deity, organ) in man is it that sees the dreams? (4) What is it in man that experiences happiness? (5) On what is all this founded? The Prashna Upanishad begins the answer with a simile to state the background of extant theory, before offering its own explanation. Like rays of the sun that withdraw into the disc as it sets and that disperse ever more as it rises, all gods (sensory organs) inside man withdraw and become one in the highest Deva named Manas (mind) when he sleeps. Other people say, asserts the Upanishad, gods that reside inside man, other than the deity of mind, cease from work in this state of sleep, and in this state, the essence of a person, his Self sleeps. The Fourth Prashna of the Upanishad, thereafter presents "five fire" theory, pointing out that Prana (breath, life-force) does not sleep, that the mind sacrifices food stored in the body with air provided by breath in order to serve the mind. Dream, states the Prashna Upanishad, is a form of enjoyment for the mind, where it reconfigures and experiences again, in new ways, what it has seen before, either recently or in past, either this life or another birth, whether true or untrue (Shaccha-Ashaccha, सच्चासच्च), whether heard or unheard, whether pleasant or unpleasant. In dream, mind beholds all. There is a deep sleep state, states the Upanishad, where impressions end and the mind too sleeps without impressions, and this is the complete state of mind relaxation, of body happiness. It is then when everything in a person retires into Atman-Brahman, including the matter and elements