Mbh 14.20.1b

[50] That is not capable of being smelt by the sense of smell; nor tasted by the tongue; or touched by the organs of touch. It is by the mind that that is attained. It is incapable of being conquered by the eye. It transcends the sense of hearing. It is destitute of scent, taste, touch, and form as attributes. It is that from which proceeds the well-ordained universe, and it is that upon which it rests. The life-breaths called Prana and Apana and Samana and Vyana and Udana flow from it, and it is that into which they again enter. The breaths Prana and Apana move between Samana and Vyana. When the soul sleeps, both Samana and Vyana are absorbed.[51] Between Apana and Prana, Udana dwells, pervading all. Hence, Prana and Apana do not desert a sleeping person. In consequence of its controlling all the life-winds, the controlling breath is called Udana. Hence, utterers of Brahman undergo penances which have myself for their goal.[52] In the midst of all those life-breaths that swallow up one another and move within the body, blazes forth the fire called Vaiswanara made up of seven flames. The nose, the tongue, the eye, the skin, the ear which numbers the fifth, the mind, and the understanding,--these are the seven tongues of that Vaiswanara's flame. That which is smelt, that which is seen, that which is drunk, that which is touched, as also that which is heard, that which is thought of, and that which is understood,--these are the seven sorts of fuel for me. That which smells, that which eats, that which sees, that which touches, that which hears numbering the fifth; that which thinks, and that which understands,--these are the seven great officiating priests. Behold, O blessed one, learned sacrificers duly casting seven libations in seven ways in the seven fires, viz., that which is smelt, that which is drunk, that which is seen, that which is touched, as also that which is heard, that which is thought of, and that which is understood, create them in their own wombs.