Which is the Real Agent in the Individual? 

The Upanishad opens with a basic question put by a sincere and inquisitive student of Brahma Vidya to his Guru. He asks his teacher:
1. Who commands and directs the mind to illumine its objects?
2. At whose command does the life-force (prana) function? 
3. At whose will do men utter speech? 
4. What power directs the eyes and the ears (and other sense organs) towards their respective objects?

Thus the disciple approached the Master and made an enquiry concerning the fundamental cause of life and human activity.  Having a sincere longing for Truth he desired to know who really sees and hears or who activates the apparent physical man. 

The student perceived all about the man, the phenomenal world, their existence etc. which could be proved and cognized by his senses. But he sought to know the invisible causal world or the prime-mover who moves the phenomenal world of which he was now only vaguely aware of; a nagging doubt that some thing must be there behind this ever-changing drama has been troubling him.  Is mind all-pervading and all-powerful, or is it being impelled by some other force, he wondered?  Who sends forth the vital energy, without which nothing can exist?  The workings of the phenomenal world seem to be directed by someone. Who is this person?

The questions put in this verse imply that the passing things of experience are not all or final but they depend on a permanent reality. The necessity of a base or ground for the existence of finite beings is assumed here. They also assume that there is a relation between reality and these phenomena, the relationship being that the former governs the latter.

BRAHMAN IS THE AGENT
The teacher replies:
It is the ear of the ear, the mind of the mind, the speech of the speech, the life of the life, the eye of the eye.  Therefore the wise, giving up the wrong notion of their self-sufficiency that they are associated with these organs, on departing from this world become immortal.

An ordinary man hears, sees, thinks, and he is satisfied to know only that much as can be known through the senses; he does not analyze and try to find that which stands behind the ear or eye or mind.  He is completely identified with his external nature.  His conception does not go beyond the little circle of his bodily life, which is concerned with the outer man only.  He has no consciousness of that which enables his senses and organs to perform their tasks.

The real power behind the sense organs is the power of the Brahman, the Self. When the Self withdraws the power from them, as happens when a person dies, none of the sense organs can exercise their functions despite their being physically present in the body.  Hence giving up the notion that “I am the sense organs” and to rise above the sense life are the necessary prerequisites to be fulfilled by a seeker for becoming immortal.

Extending this thought further, ordained by whom this world appears to be real? Because Brahman is behind this world it appears to be real just as because of the rope lying on the ground, the superimposition of a snake on it appears to be real. If you take away the rope, there will be no snake. Similarly take away the Brahman, there will be no world.

The universe is real only through the existence of that One Reality in it. It is as Sri Ramakrishna said, “zeros have no value, but by adding the figure 1 before a zero it gets value and it increases with the addition of every zero. Infinity of zeros has no value until you have the figure of 1 before it. That one is pure Consciousness with respect to the universe of objects and events (which like zeros have no intrinsic value).”

The teacher continues:
There the eye does not go, nor speech, nor mind.  We do not know That; we do not understand how It can be taught.  It is distinct from the known and also It is beyond the unknown.  Thus we have heard from the ancient (teachers) who told us about It.

These physical eyes are unable to perceive that subtle essence which is called the Brahman.  Nor can it be expressed by finite language or known by finite intelligence, because it is infinite.  Our conception of knowing finite things is to know their name and form; but knowledge of Brahman is distinct from such knowledge.

Knowledge of a thing arises through the senses or the mind and since Brahman is not reached by either of these, we do not know of what nature it is. We are therefore unable to understand how anyone can explain that Brahman to another.

Whatever is perceivable by the senses, that it is possible to indicate to others by species, quality, function or relationship (jati, guna, kriya, visesana). Brahman does not possess any of these differentiating characters. Hence the difficulty in explaining its nature to others.

Brahman is above the known and the unknown. But it is not unknowable. What is suggested is that this teaching has been transmitted by tradition. We cannot know it by logic. “Those who know do not speak; those who speak do not know.”

Teacher says:
“That which speech does not illumine, but which illumines speech, know that alone to be the Brahman (the Supreme Being), not this which people worship here.
That which cannot be thought by mind, but by which, they say, mind is able to think, know that alone to be the Brahman, not this which people worship here.
That which is not seen by the eye, but by which the eye is able to see, know that alone to be the Brahman, not this which people worship here.
That which cannot be heard by the ear, but by which the ear is able to hear, know that alone to be Brahman, not this which people worship here.
That which cannot be smelt by the nose, but by which the nose is able to smell, know that alone to be Brahman, not this which people worship here.”

The underlying idea of these verses is that the sense organs like mind, eyes, ear, etc, are powerless by themselves. They require some power to make them function. What is that power? It is the source of all power which is described as Brahman or the Self. Brahman is the Supreme Reality on which everything rests. It is compared to the hub of a wheel.

Our wisdom lies in realizing that Supreme Power instead of getting obsessed with the sense world which is not real. Here we must be clear that when the world is stated to be not real, it means that it is subject to constant modifications or change. According to Vedanta, that which changes is unreal (anitya) and that Brahman alone is real (nitya) for it never changes. If the world appears as real it is because of the super-imposition of the world on Brahman which supports it just as the rope supports the illusory vision of a snake which is superimposed on the former. Independent of Brahman, the world cannot exist just as there cannot be any snake without a rope.

In this knowledge, When these verses say “know that alone to be Brahman, not this which people worship here” it means that God ceases to be a conceived and apprehended entity and becomes the inward power by which we live.