By tracing the source of the mind or universe one will be able to realize the Brahman.

When Upanishad itself declares:- sarvam khalvidam Brahma - all this (universe) is verily Brahman. By following back all of the relative appearances in the world, we eventually return to that from which it is all manifest – the non-dual reality (Chandogya Upanishad). 

Then it is no use going roundabout way, trace the Brahman which is the formless substance and the witness of the universe, which is in the form of mind. By tracing the source of the mind or universe one will be able to realize the Brahman. 

The ultimate truth has nothing to do with the Scriptures and it is independent of scriptures. The point is: though it is taught by the Vedas, it does not require any belief in the infallibility of the Vedas; in other words even if an individual or some other religion were to propose the same thing, a person with an open mind would come to the same conclusion that there is a formless witness, that it is Brahman - and that it is the same as the self ,which is not an individual but it pervades in everything and everywhere in three states as their formless substance and witness.

When Sri,Sankara says: world is unreal . He never said body is unreal. He would have said only birth and death is unreal but he did not say that, he said the world is unreal. He meant the world including the body, because the body and the world appear together and disappear together (waking or dream). Then we have to think, what remain without the body and the world as reality. How can the birth, life, death, rebirth, and reincarnation, which take place in an unreal world (waking or dream), can be true. The one, which is aware of the birth, life death, rebirth and reincarnation (illusion or unreal), is formless reality, which is the true self/true identity. The formless self is your true identity, which is birthless and deathless but it is the witness of the birth, life and death and rebirth (illusion or unreal).

On the standpoint of   the formless soul , the innermost self , the  experience of birth, life, death, rebirth and reincarnation theory is part of the illusion/unreal. The body cannot reincarnate, the body and the world are created out of the same formless stuff. Until one views and judges on the base of flesh, bone and blood [five elements], he will not be able to grasp the non-dual truth. Thus, one must know on what standpoint we are not born and we do not die thoroughly, just by hearsay views, it will not lead anyone to the non-dual destination.