This Soul of mine within the heart is smaller than a grain of rice, or a barley-corn, or a mustard-seed, or a grain of millet, or the kernel of a grain of millet; this Soul of mine within the heart is greater than the earth, greater than the atmosphere, greater than the sky, greater than these worlds.

— Chandogya Upanishad

Erich Frauwallner in his 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. Frauwallner places the Brahmana period between 800 - 600 B.C. We will examine these Upanishads first.

In these Upanishads the "space of the heart" is the domain of Brahman.

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 (i.e. the 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 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." (Chan. 8.1- 8.3; see also Chan. 3.12.9 and Brih. 4.22, 4.422, 5.3, 5.6)

The heart is also the locale of deep sleep. (Brih. 2.1-17, 4.3. 19- 21; Chan. 8.6-3). That the state of deep sleep is identical to Brahman is affirmed by several passages such as the following:

As a falcon, or an eagle, having flown around here in space, becomes weary, folds its wings, and is borne down to its nest, just so this person hastens to that state where, asleep, he desires no desires and sees no dream.

This, verily, is that form of his which is beyond desires, free from evil, without fear. As a man, when in the embrace of a beloved wife knows nothing within or without, so this person, when in the embrace of the intelligent Soul, knows nothing within or without. Verily, that is his (true) form in which he is without desire and without sorrow. (Brih. 4.3-19 & 211 see also Brih. 4.3.7; Chan. 6.8, 6.9.1, 8.4.2, 8.6.3; Kaus. 4.19)

Atman (=Brahman) is the light of the heart, transcending this world and the forms of death. (Brih. 4.3.7)

In dream-sleep, the intermediate state between waking and deep-sleep, the intelligence (vijnana) "moves around in his own body as he pleases." (Brih. 2.1.18). Also described in connection with sleep are the channels of the heart called hita. "Now, when one is thus sound asleep, composed, serene, he knows no dream; then he has crept into these channels..." (Chan. 8.6.3; also Kaus. 4.19) The channels of the heart are, numbered at seventy-two thousand at one point (Brih. 2.1.19), and a hundred and one at another (Chan. 8.6.6). Some references say that these channels are filled with five different colors, "as a hair subdivided a thousandfold, so minute are they, full of white, blue, yellow, green, and red." (Brih. 4.3.19; also Chan. 8.6.1) In Chan. 8.6.1- 3, these channels are the connecting links to the rays of the sun, by which "the Fire of life enters into men and returns back again into the Sun after Death." These sunrays which "extend from yonder sun and creep into these channels" are the chains which keep men bound to the continual rounds of birth and death. Freedom, however, is available to those with the saving knowledge. At death,

when he thus departs from this body, then he ascends upward with these very rays of the sun. With the thought of OM, verily, he passes up. As quickly as one could direct his mind to it, he comes to the sun. That, verily, indeed, is the world-door, an entrance for knowers, a stopping for non-knowers. (Chan. 8.6.5)

Thus, the knowers rise up, released, to the heavenly world, while the non-knowers must again experience the agony of rebirth.

Another description of death utilizes what Frauwallner calls the oldest explanation of sleep to present a slightly different version. According to this idea, there are two "manikins" which constitute the soul, Indra of the right eye, and his spouse Indrani of the 1eft. At sleep these two soul-manikins withdraw from the eyes and unite in the heart, whereupon a man sinks down into sleep. "Their meeting place is the space in the heart... The path that they go is that channel which goes upward from the heart." (Brih. 4.2-3) Indra is usually referred to as the Person in the eye and is identical to Brahman as well as the to the Person in the sun-disk. (Brih. 2.3.5, 2.3.3, 2.5.5) The Person in the eye is the soul with reference to the waking hours, while at sleep it sinks into the heart and resides their in union with its spouse, which explains the bliss of the deep-sleep state.

In this second version of death, the Person turns away from the sun and thus "becomes non-knowing of forms." (Brih. 4.4.1) Then he descends into the heart which "at the point" becomes lighted up. "By that light the self departs, either by eye, or by the head, or by other bodily parts." (Brih. 4.4.1-2) In this second version there are various ways of departing from the heart. A bit farther on in this Upanishad one comes to two verses which seem to imply a distinct path for knowers of Brahman, though still connected to the colored channels and the sunrays.

The ancient narrow path that stretches far away has been touched by me, has been found by me. By it the wise, the knowers of Brahma, go up hence to the heavenly world, released.

On it, they say, is white and blue and yellow and green and red. That was the path by Brahma found; By it goes the knower of Brahma, the doer of right and every shining one. (Brih. 4.4.8-9)

Finally, we come to a verse that is often quoted as a direct allusion to kundalini yoga with its emphasis on the ascent of "energy" to the crown of the head. It is indeed an unique reference, maintaining, on the one hand, that that there exists a hundred and one channels of the heart rather than seventy-two thousand, and, on the other hand, indicating that the "channel of immortality" passes up to the crown of the head.

There are a hundred and one channels of the heart. One of these passes up to the crown of the head. Going up by it, one goes to immortality. The others are for departing in various directions. (Chan. 8.6.6)

It is curious that this verse directly follows paragraphs which depicts a direct connection between the heart channels (described with colors and thus appears to be the seventy-two thousand version) and the sun. This verse quoted above certainly seems out of place here. Its contribution, in view of our subject, is the all important teaching of a channel of immortality which rises from the, heart to the crown of the skull.

2. The Later Upanishads

His form is not to be beheld.
No one soever sees Him with the eye.
They who thus know Him with heart and mind
As abiding in the heart, become immortal.

- Svetasvatara Upanishad

 

The later Upanishads maintain many of the teachings of the older Upanishads while adding much in the way of new material. Prasna Upanishad, for instance, combines the above teaching of a hundred and one channels with that of the seventy-two thousand varied colored one. "Here there are those one hundred and one channels. To each of these belong a hundred smaller channels. To each of these belong seventy-two thousand branching channels."(3.6) Another synthesis is made in the next paragraph when it is said that by "rising upward through one of these (channels), the upbreath (udana) leads in consequence of good (work) to the good world; in consequence of evil, to the evil world; in consequence of both, to the world of men." (Prasna 3.7) Here we have one isolated channel that carries everyone to their respective ends, instead of separate channels or routes for the "knowers and nonknowers." But then the "good world" need not necessarily be the equivalent to immortality in Brahman. Maitri 6.30 speaks of varied colored rays, one of which pierces the sun and extends to the Brahman world. The other hundred, however, go elsewhere.

What are its other hundred rays,
Are similarly upwards ranged;
Thereby unto the various gods'
Abiding places one arrives.
But by its feebly shining rays
which manifoldly downward lead
One roams about here helplessly
For the consuming of his deeds.

We learn here of three possible destinies, the highest course or the Brahman world, the abodes of gods, and the world of men. Thus, only one leads to immortality, though no reference is here made to the crown of the head.

By the time of the Maitri Upanishad (6.21) there is the teaching that by the medium of a yoga process one may rise through a channel now called Sushumna to the unlimited.

There is a channel called the Sushumna, leading upward, conveying the breath, piercing through the palate. Through it, by joining the breath, the syllable OM, and the mind, one may go aloft. By causing the tip of the tongue to turn back against the palate and by binding together the senses, one may, as greatness, perceive greatness. Thence he goes to selflessness. Because of selflessness, one becomes a nonexperiencer of pleasure and pain; he obtains the absolute unity (kevalatva) For thus has it been said:

After having first caused to stand still
The breath that has been restrained, then,
Having crossed beyond the limited, with the unlimited
One may at last have union in the head. (Maitri 6.21)

In this paragraph we have an unmistakable reference to a practice which through breath control enables a man to ascend to union in the head which is variously named selflessness, unity, the unlimited. Retention of breath and manipulation of the tongue are both practices which are central to the later day Hatha yoga discipline.

In Svetasvatara (2.8- 2.13), we find more references to this

same yoga practice.

Having repressed his breathings here in the body, and having his movements checked, one should breathe through his nostrils with diminished breath. Like that chariot yoked with vicious horses, his mind the wise man should restrain undistractedly.(Svet. 2.9)

No sickness, no old age, no death has he who has he who has obtained a body made out of the fire of Yoga. (Svet. 2.12)

This section also speaks of the appearance of certain psychic signs such as smoke, sun, lightning, and moon which are the preliminary manifestations of Brahman in yoga. As we shall see, these signs are also recorded in later yogas in which they are assigned to the stage when prana enters Sushumna.

The teachings connected with traveling via the channels or sunrays is limited to a very few stanzas in all the Upanishads. It is not necessary to go anywhere to realize Brahman and through the medium of the bodily metaphor of the heart in the later Upanishads, this basic teaching is communicated.

A Person of the measure of a thumb is the inner soul, ever seated in the heart of creatures. He is ever framed by the heart, by the thought, by the mind. They who know That, become immortal. (Svet- 3.13, 4.17, 4.20)

...having crossed over with the raft of the syllable OM to the other side of the space in the heart, in the inner space which gradually becomes manifest one should enter the hall of Brahma, as the miner seeking minerals enters into the mine. (Maitri 6.28)

Thus, when the heart space is known as identical to Atman-Brahman, the seer becomes That. As Mundaka (2.1-10) puts it: "He who knows That, set in the secret place (of the heart), he here on earth, my friend, renders asunder the knots of ignorance." Elsewhere, the heart is compared to knots which, when unraveled, bestows immortality. (Katha 6.15; Mund. 2.2.8, 3.2.9; also Svet. 4.20)

Another stanza speaks of a light that becomes manifest in the space of the heart through a yogic process. The object is to uncover the heat which is hidden in the ether of the heart.

By intense concentration they so disperse the space in the heart that the light, as it were, of that (heart) appears...

When this light manifests, "one passes speedily into the same condition (of light)" and "thought together with its support vanishes away."

The ether-storehouse of the heart
Is bliss, is the supreme abode!
This is ourself, our Yoga too;
And this, the heat of fire and sun. (Maitri 6.27)

Further on in the Maitri Upanishad one comes to a section about the length of a dozen verses which Hume entitles 'Liberation in the control of one's thoughts." (Maitri 6-34) It is a celebration of meditation and one is advised that "the mind should be confined, till in the heart it meets its end." (Maitri 6.34; also Svet. 2.8) In the heart, the abode of Brahman, one may realize freedom and immortality through yoga.