The following is Eknath Easwaran’s description of Atman and Brahman in the Introduction to his translation and commentary on the Upanishads.
“In meditation, as the mind settles down to dwell on a single focus, attention begins to flow in a smooth, unbroken stream, like oil poured from one container to another. As this happens, attention naturally retreats from other channels. The ears, for example, still function, but you do not hear; attention is no longer connected with the organs of hearing.
When concentration is profound, there are moments when you forget the body entirely. This experience quietly dissolves physical identification. The body becomes like a comfortable jacket: you wear it easily, and in meditation you can unbutton and loosen it until it scarcely weighs on you at all.
Eventually there comes a time when you get up from meditation and know that your body is not you. This is not an intellectual understanding. Even in the unconscious the nexus is cut, which means there are sure signs in health and behavior: no physical craving will be able to dictate to you, and any compulsion to fulfill emotional needs through physical activities will vanish. Most important, you lose your fear of death. You know with certitude that death is not the end, and that you will not die when the body dies.
The Taittiriya Upanishad says that the body is the first of many layers that surround the human personality, each less physical than the one before. These are, roughly, components of what we call “mind”: the senses, emotions, intellect, will. As awareness is withdrawn from these layers of consciousness one by one, the sages gradually made another astonishing discovery: the powers of the mind have no life of their own. The mind is not conscious; it is only an instrument of consciousness – or, in different metaphors, a process, a complex field of forces. Yet when awareness is withdrawn from the mind, you remain aware. When this happens you realize you are not the mind, any more than you are the physical body.
When awareness has been consolidated even beyond the mind, little remains except the awareness of “I.” Concentration is so profound that the mind-process has almost come to a standstill. Space is gone, and time so attenuated that it scarcely seems real. This is a taste of shanti, “the peace that passeth understanding,” invoked at the end of every Upanishad as a reminder of this sublime state. You rest in meditation in what the Taittiriya Upanishad calls the “body of joy,” a silent, ethereal inner realm at the threshold of pure being.
For a long while it may seem that there is nothing stirring in this still world, so deep in consciousness that the phenomena of the surface seem as remote as a childhood dream. But gradually you become aware of the presence of something vast, intimately your own but not at all the finite, limited self you had been calling “I.”
All that divides us from the sea of infinite consciousness at this point is a thin envelope of personal identity. That envelope cannot be removed by any amount of will; the “I” cannot erase itself. Yet, abruptly, it does vanish. In the climax of meditation the barrier of individuality disappears, dissolving in a sea of pure, undifferentiated awareness.
This state the Upanishads call turiya – literally “the fourth,” for it lies beyond waking, dreaming, and dreamless sleep. Turiya, the Upanishads say, is waking up in dreamless sleep: in the very depths of the unconscious, where one is aware of neither body nor mind. In later Hindu thought this awakening will receive more familiar names: samadhi, “complete absorption”; moksha, “liberation” or “release,” for it brings freedom from all conditioning and the limitations of time and space.
What remains when every trace of individuality is removed? We can call it pure being, for it is in differentiating this unity that created things acquire their name and form. The sages called it Brahman, from the root brih, “to expand.” Brahman is the irreducible ground of existence, the essence of every thing – of the earth and sun and all creatures, of gods and human beings, of every power of life.
Simultaneous with this discovery comes another: this unitary awareness is also the ground of one’s own being, the core of personality. This divine ground the Upanishads call simply Atman, “the Self” – spelled with a capital to distinguish it from the individual personality. In the unitive state the Self is seen to be one, the same in everyone. This is not a reasoned conclusion; it is something experienced at the very center of one’s being, an inalienable fact. In all persons, all creatures, the Self is the innermost essence. And it is identical with Brahman: our real Self is not different from the ultimate Reality called God.
This tremendous equation – “the Self is Brahman” – is the central discovery of the Upanishads. Its most famous formulation is one of the mahavakyas or “great formulae”: Tat tvam asi, “You are That.” “That” is the characteristic way the Upanishads point to a Reality that cannot be described; and “you,” of course, is not the petty, finite personality, but that pure consciousness “which makes the eye see and the mind think”: the Self. In this absorption there is no time, no space, no causality. These are forms imposed by the mind, and the mind is still. Nor is there awareness of any object; even the thought of “I” has dissolved. Yet awareness remains: chit, pure, undifferentiated consciousness, beyond the division of observer and observed. When the mind-process starts up again, as it must, and we slip back into body and personality, the multiplicity of the perceptual world will unfold as a seed bursts into a tree.
Astrophysicists use similar language when they talk about creation. All the matter in the universe must have been present in that “primeval atom,” supercondensed to an unbelievable degree. In such a state, matter would no longer be possible as matter. It would be stripped down to pure energy, and energy itself would be raw and undifferentiated; variations like gravity and light would not have emerged. Time would not yet be real, for there can be no time before zero; neither would space make sense in the context of a question like, “What was there before the Big Bang?” Physicists reply, with Gertrude Stein, “There’s no ‘there’ there. There’s no ‘then’ then.” Space and time, matter and energy, sprung into existence at the moment of creation; “before” that moment the concepts do not apply.
The sages would find all this a perfect metaphor for the unitive state. In samadhi, reality is condensed into pure potential, without dimensions, without time, without any differentiation. Physicists do not say there was nothing before the Big Bang; they say everything came from that, and nothing more can be said. Similarly, samadhi is not emptiness but purnata: plenitude, complete fullness. The whole of reality is there, inner as well as outer: not only matter and energy but all time, space, causality, and states of consciousness.
That fullness the Upanishads call sat: absolute reality, in which all of creation is implicit as an organism is implicit in DNA, or a tree in a tiny seed.
The joy of this state cannot be described. This is ananda: pure, limitless, unconditioned joy. The individual personality dissolves like salt in a sea of joy, merges in it like a river, rejoices like a fish in an ocean of bliss. “As a man in the arms of his beloved,” says the Brihadaranyaka daringly, “is not aware of what is without and what within, so one in union with the Self is not aware of what is without and what within, for in that state all desires are fulfilled.” And what other scripture would cap such an image with a pun? “Apta-kamam atma-kamam akamam rupam: That is his real form, where he is free from all desires because all his desires are fulfilled; for the Self is all our desire.”
Nothing less can satisfy the human heart. “There is no joy in the finite; there is joy only in the infinite.” That is the message of the Upanishads. The infinite – free, unbounded, full of joy – is our native state. We have fallen from that state and seek it everywhere: every human activity is an attempt to fill this void. But as long as we try to fill it from outside ourselves, we are making demands on life which life cannot fulfill. Finite things can never appease an infinite hunger. Nothing can satisfy us but reunion with our real Self, which the Upanishads say is sat-chit-ananda: absolute reality, pure awareness, unconditioned joy.”