It is the soul, which was in ignorance, experiences the duality as reality.

The soul is the innermost self. The soul is present in the form of consciousness.  It is the soul, which was in ignorance, experiences the duality as reality. When it wakes up to its own true nature there is neither the ego, nor body, nor the world remains as reality.  The soul alone remains in its own formless non-dual true nature, in   its  self - awareness.

The dream becomes unreal when waking takes place. Similarly the waking becomes unreal when wisdom dawns.  Limiting the consciousness to waking or dream (duality) is erroneous.  It was present even in deep sleep without the body and without the world (without waking or dream). If consciousness was no there is deep sleep than one will not say he had sound sleep in waking experience. Therefore perfect understanding of ‘what is what’ leads to nondual self-awareness in midst of duality. 

Perfect  understanding of ‘what is what’ leads to non-dual self-awareness in midst of duality.

For that one has to drop all the accumulated knowledge based on the ego (waking entity), which is the false self within the false experience (waking). And learn to view and judge the three states on the base of the formless soul or consciousness, the innermost self, because whatever based on the ego (waking entity) leads to intellectuality. 

Intellectuality is based on individuality. Individuality is falsehood because the self is not an individual because it is formless. The formless soul or consciousness pervades in everything and everywhere in all the three states as their formless substance and witness. In the realm of truth the formless substance and witness are one in essence. The essence is consciousness. Thus consciousness alone is real and all else mere illusion because there is no second thing exist other than consciousness.