The Upanishads, Part 2 (SBE15)
Chapters
Prasna-Upanishad: Sixth Prapathaka

who knows this is possessed of food, breath, mind, knowledge, and joy. Whatever creatures here on earth eat food, abiding in them he, who knows this, eats food. Food has been called undecaying, food has been called worshipful; food is the breath of animals, food is the oldest, food has been called the physician.

14. And thus it has been said elsewhere: Food is the cause of all this, time of food, and the sun is the cause of time . The (visible) form of time is the year, consisting of twelve months, made up of Nimeshas (twinklings) and other measures. Of the year one half (when the sun moves northward) belongs to Agni, the other to Varuna (when the sun moves southward). That which belongs to Agni begins with the asterism of Magha, and ends with half of the asterism of Sravishtha, the sun stepping down northward. That which belongs to Soma (instead of Varuna) begins with the asterism (of Aslesha), sacred to the Serpents, and ends with half of the asterism of Sravishtha, the sun stepping up southward. And then there (are the months) one by one, belonging to the year, each consisting of nine-fourths of asterisms (two asterisms and a quarter being the twelfth part of the passage of the sun through the twenty-seven Nakshatras), each determined by the sun moving together with the asterisms. Because time is imperceptible by sense, therefore this (the progress of the sun, &c.) is its evidence, and by it alone is time proved to exist. Without proof there is no apprehension of what is to be proved; but even what is to be proved can become proof, for the sake of making itself known,

if the parts (the twinklings, &c.) can be distinguished from the whole (time ). For thus it is said:

'As many portions of time as there are, through them the sun proceeds: he who worships time as Brahman, from him time moves away very far.' And thus it is said:

'From time all beings flow, from time they grow; in time they obtain rest; time is visible (sun) and invisible (moments).'

15. There are two forms of Brahman, time and non-time. That which was before the (existence of the) sun is non-time and has no parts. That which had its beginning from the sun is time and has parts. Of that which has parts, the year is the form, and from the year are born all creatures; when produced by the year they grow, and go again to rest in the year. Therefore the year is Pragapati, is time, is food, is the nest of Brahman, is Self. Thus it is said:

'Time ripens and dissolves all beings in the great Self, but he who knows into what time itself is dissolved, he is the knower of the Veda.'