By holding on to theories one remains in the realm of duality

By holding on to theories one remains in the realm of duality. One has to mentally go on dropping what is not truth through deeper self-search. Finally when one becomes aware of the fact that, his ego, his body and the world are one in essence  than there is self-awareness in the midst of duality.  In non-dual self-awareness, the ego is not considered as ego, even though ego is present, the body is not considered as body even though body is present, the world which confronts him is not considered as world even though the world is present , the duality ceases even though  the duality  is present  because of wisdom everything is considered as consciousness. Thus there is conscious oneness.

When self becomes aware of its formless non-dual nature it becomes empty of ignorance or illusion or duality or experience of waking or dream.  Thus whatever remains empty of duality or ignorance or illusion is non-dual reality. Only through wisdom one becomes aware of the truth in the midst of duality.

 That is why "Sri, Sankara said: - Without causing the objective universe to vanish and without knowing the truth of the Self, how is one to achieve Liberation. -63- (VC)”

Universe in which we exist will not remain as reality when wisdom dawns. Universe is mere mirage created out of consciousness and there is conscious awareness of unity in diversity because there is no second thing exist other than consciousness.