The History of Indian Philosophy divides the thirteen principle Upanishads into two groups, those of the Brahmana period and those which originate later. Those of the Brahman period are seven, Brhadarnayaka, Chandogya, Kausitaki, Isa, Taittiriya, Aitareya, and Kena, with the Brhadarnayaka (Brih) and Chandogya (Chand) as the eldest of this group. The Brahmana period is between 800 - 600 B.C. In these earlier ones, the "space of the heart" is the domain of Brahman. Here is an excerpt:
Now what is here--in this city of Brahma [explained by Sankara as the body] is an abode, a small lotus flower. Within that is a small space. What is within that should be searched out; that, assuredly, is what one should desire to understand.
If they [pupils] should say to him: "This abode, the small lotus-flower that is here in this city of Brahma, and the small space within that, what is there that should be searched out, which assuredly one should desire to understand?"
He should say: "As far, verily, as this world-space "(ayamakasa) extends, so far extends the space within the heart. Within it, indeed, are contained both heaven and earth, both fire and wind, both sun and moon, lightning and the stars, both what one possesses here and what one does not possess; everything here is contained within it."
©1999 John Scanlan/All Rights Reserved