The earliest ancient sages used the word ‘I’ to the formless witness of the three states not to the ego as moderns use it and think the ‘I’ without the body as self.

The earliest ancient sages used the word ‘I’ to the formless  witness of the three states not to the ego as moderns use it and think the ‘I’ without the body as self.  Deeper self-search reveals the   fact that,  ‘I’ is not the self but the formless  witness of the ‘I’ is the true self.  The formless witness is the soul,which is present in the form of consciousness. Consciousness  is real and  eternal. 

People think that the ‘soul’ or ‘spirit’ is something different from the mind. They believe that the mind is really two. This is the confusion among religious believers  and intellectuals. If ‘Soul’ has any meaning, if ‘spirit’ has any meaning, so long as one thinks of them, they are merely ideas. No, Mind is the highest: it is consciousness, non-dual wisdom.

The individual is a bundle of memories, desires within the waking or dream. The memories and desires are part of the duality. Therefore the individual self is entirely part and parcel of the mirage. Peoples' ideas of that they will go to some world after death, some astral plane or religious heavens will disappear as nonsense with the disappearance of belief in the reality of the ‘I’.  

Bhagwan Raman Maharshi :- Take Vedanta, for instance: it speaks of 15 pranas the names and functions of it   which the student is asked to commit memory. Will it not be sufficient if he thought only one prana does the whole work of maintaining the body? Again the antakaran is said to think, to desire, to will, to reason etc. Why all these details? Has anyone seen antakarana, or all these pranas? Do they really exist? They are conceptual divisions invented by teachers of philosophy by their excessive analysis. Where do all these concepts end? Why should confusion created and then explained away? Fortunate is the man who does not lose him self in the labyrinths of philosophy, but goes straight to the source from which they all arise. (GURU RAMANA .By S.S Cohen -vii Danger of philosophy-Page -58-59)

 And it is very true.

 The truth has to be proved without the scriptural authorities. The scriptural authorities cannot be accepted as proof until it is verified thoroughly in the path of truth or wisdom. Intellectually knowing the truth is only an imagination, whereas realizing the truth knowing  it as such.

Truth is not only that which is beyond contradiction, but also that in which is no possibility of contradiction. Such a state can only be realized as non-duality, where there is no second thing. The illustration for that is deep sleep but sleep is not the ultimate reality. It is merely an analogy. "If one thinks there is another entity whether man or God there is no truth." This is the truth of those who have inquired and reasoned on the true base.

What is ‘I’? The ‘I’ disappears in deep sleep, so what is the use of being attached to it? It is illusory.

There is really no ‘I’. It dies in deep sleep. But the notion of its unreality will gradually grasp by the serious and receptive seekers. Individuality is illusory.

One is ignorant of the fact that the ‘I’  or mind(universe) comes and goes as waking or dream and has no permanent existence, is only a mirage after all.

Formless soul  cannot be known in the sense in which one knows objects of thought. It can be known only to the extent to which one knows them, for he can only think of the knower when he is in the presence of the known, i.e. Objects, for the latter makes him aware that a knower must exist. Thus duality makes one think of the knower, but it cannot make him know the knower. The knower is known in the world or waking only by implication, as one cannot think without a knower. The knower is a concept, and cannot be known in itself.

The witness is only one. Why and how? The word seer or witness is got at by eliminating the seen (universe or waking or dream) mentally. There never have been two seers/witnesses; if there be two one becomes seen to the other.

When one thinks seer or witness is the ego; he is mistaking the formless soul, for the ego which appears and disappears. This is the great stumble block in understanding and assimilating the nondual or Advaitic  truth.  Everyone thinks that when ego is not, nothing remains. When one is aware of the ego, there must be the formless knower, which is the formless  soul, which is in the form of consciousness. This directly opposed to all other systems. How can one talk of ego unless there is something which witnesses it as known.

The seeker has to analyze the whole mental experiences (dual or nondual).Psychology does not go beyond duality or mind or the universe. But who sees this analysis? The one which is conscious of the relation between subject and object is the soul or consciousness the innermost self. It is that of which everyone is absolutely certain and it cannot be proved. It is self-evident.