By Realizing the fact that, the true self is not ‘I’, but the Atman/soul, is the key that opens the door of non dual reality.

 YOGA VASISHTA:-

The mind, the intellect, the senses, etc. are all the play of Consciousness. They are unreal and seem to exist only due to lack of insight. 

I, the pure, stainless and infinite Consciousness beyond Maya, look upon this body in action like the body of another.

If one realizes the unity of things everywhere, one always remains tranquil, inwardly cool and pure like space without the sense of 'I'.

Just as the whole tree with all its future ramifications is in the seed, the entire universe of the past, the present and the future is contained in the atom of infinite consciousness.

Therefore, though the self is neither the doer of actions nor the experiencer of experiences, it is the doer of all actions and the experiencer of all experiences: there is nothing apart from it.

Within the atom of infinite consciousness the doer-ship and the experiencer are inherent.

The world, however, has never really been created, nor does it disappear: it is regarded as unreal only from the relative point of view, from the absolute point of view it is non-different from the infinite consciousness.

Ignorant is struck with awe or reverence at the outer indications of renunciation, and thus they take a religious scholar or God men to be a Gnani. But the religious scholar or Guru or  God men have no connection with the non dual wisdom.

By having no wife, no family, and no possessions" is not the qualification to acquire the non dual wisdom. By repressing these desires is anything to do in pursuit of truth. 

The first step is of knowing “the true Self." The second is to know the true self is the soul  or the Atman." Then alone one knows the non dual truth and wisdom, i.e. the Atman is the ultimate truth.

Realizing the fact that, the true self is not ‘I’, but the Atman/soul, is the key that opens the door of non dual reality.

 This yoga helps only to stabilize the restlessness of the mind. The formula "What is I?" presupposes the existence of an ‘I’. ‘I’ is only an assumption. Before proceeding to act on such a formula seeker ought first to inquire whether ‘I’ is the self or not. 

 Pursuit of truth starts from what one sees as a person, i.e. the world.  Non dual wisdom comes from both knowing the world and the true self. To leave out one of these parts is to prevent the attainment of non dual wisdom.

"What is “I” is useful and certainly has a value, and gives some clue of the true self as the Witness and the witnessed. The man and the world face the formless soul the innermost  self. This truth has to be grasped. If the  witnessed (waking or dream) is ignored, then  it  cannot give the full truth.

Who am ‘I’? - inquiry exposes only the falsehood of the form; thus it is incomplete. ‘ What is ‘I’?’   deals with the three states, whereas the ‘Who am I?’ deals with a part only.

"Who am I" is physical  based, because there, is no person in the realm of truth but only in the illusion. The right way of inquiry is “What is I?"

To reflect  on “What am   I?" can only yield the thought 'I', just as the yogi  who says "I will not think of the beautiful woman" will end up by always thinking of her.

The inquiry “Who am I” is egocentric, not a soul-centric  inquiry. It is centered on physicality and individuality. It is purely ego-centered. Seeker of truth has to lift their thoughts above ego and ask "What is ‘I’? ‘What is mind? What is this world?"

All the experiences of the three states  put together make the  soul or Atman, not merely the ego which is present only in waking or dream questioning itself ''What am I?.”