Khandogya-Upanishad: Eighth Prapathaka, First Khanda
1. Harih, Om. There is this city of Brahman (the body), and in it the palace, the small lotus (of the heart), and in it that small ether. Now what exists within that small ether, that is to be sought for, that is to be understood.
2. And if they should say to him: “Now with regard to that city of Brahman, and the palace in it, i.e. the small lotus of the heart, and the small ether within the heart, what is there within it that deserves to be sought for, or that is to be understood.”
3. Then he should say: “As large as this ether (all space) is, so large is that ether within the heart. Both heaven and earth are contained within it, both fire and air, both sun and moon, both lightning and stars; and whatever there is of him (the Self) here in the world, and whatever is not (i.e. whatever has been or will be), all that is contained within it.”
4. And if they should say to him: “If everything that exists is contained in that city of Brahman, all beings and all desires (whatever can be imagined or desired), then what is left of it, when old age reaches it and scatters it, or when it falls to pieces?” Then he should say: “By the old age of the body, that (the ether, or Brahman within it) does not age; by the death of the body, that (the ether, or Brahman within it is not killed. That the Brahman) is the true Brahma-city (not the body). In it all desires are contained. It is the Self, free from sin, free from old age, from death and grief, from hunger and thirst, which desires nothing but what it ought to desire, and imagines nothing but what it ought to imagine. Now as here on earth people follow as they are commanded, and depend on the object which they are attached to, be it a country or a piece of land,
6. “And as here on earth, whatever has been acquired by exertion, perishes, so perishes whatever is acquired for the next world by sacrifices and other good actions performed on earth. Those who depart from hence without having discovered the Self and those true desires, for them there is no freedom in all the worlds. But those who depart from hence, after having discovered the Self and those true desires, for them there is freedom in all the worlds.