'I' is the state of ignorance.

Man  and his experience of the world are  the product of ignorance.  The ignorance is present as 'I'.  'I' is present as mind. Mind is present as universe. Universe appears as waking or dream . Man has been conditioned to think and be and behave and believe and live as an individual separate from the world. Therefore, the self has been identified with physical body with the name within the waking experience.'I' is the state of ignorance. If  there is 'I' there is duality. If there is duality then there is separation. if there is separation there is illusion.  if there is illusion then unreality is experienced as reality.    

The ‘mind’ is the whole  Waking or dream experience. The Waking or dream is not the experience of the physical body but of the formless  Soul, the innermost Self because the physical body and the world are within the waking or dream. 

The man and his world are within the mind; therefore mind is not within the brain. This has to be understood to assimilate the self-knowledge. Without understanding this fact the assimilation is impossibility.  

The nature of the Self is formless non-dual.  The nature of the mind is duality or diversity. The self is the formless substance of the mind  or duality  or diversity. Therefore, the whole experience of the diversity created out of single stuff.  Therefore, there is no division in ultimate standpoint is the self, which in the form of consciousness. Viewing the worldview on the base of the physical self is the cause of division and separation.  

  When the seekers become aware of the fact that the true self is not physical but the soul, he becomes aware of the fact that the mind is mere illusion.   The one who is ignorant of the true self experiences the duality as reality.

A person perceives the world within the mind.  Absent of mind is absent of waking or dream. Thus waking or dream is mind.

One thinks he is an individual separate from the world within the mind. He is unaware of the fact that the mind is not within his brain, but he and his experience of the world are within the mind.  Thus, he thinks he is born in this world and world existed prior to him. Thus this conviction makes him believe the birth, life and death as reality.  Until this conviction is thee he will   views and judges the worldview on the physical base, which is the cause of ignorance of the fact that, the true self is the soul.

This ignorance of the true self is the main hurdle in pursuit of truth. Therefore, it is very much necessary to rectify the seeking base from physical (form) to spirit (formless) before proceeding further in pursuit of truth.

If the reasoning  base is not rectified  than it will lead one towards hallucination. When the mind itself is myth then the man and his experience of the world is bound to be myth. Therefore perfect understanding of the mind will help one to unfold the mystery of the mind.  It is impossible to unfold the truth on the base of false self within the false experience, because the truth is prior to the appearance of the falsehood.  And falsehood creates ignorance.

Seeker has to burn down the ignorance by rectifying the base of reasoning by realizing the fact that self is not physical but it is the formless consciousness.