The experience of birth, life, death and the world is reality within the waking experience. The innermost Self is nothing to do with the experience of birth, life death because it is birthless. The one, which is born, lives and dies is in the world is the waking entity. Waking entity is not the self. The self is that, which witnesses the coming and going of the three states without the physical apparatus. The experience of birth, life, death and the world (waking) is an object to the formless subject (soul, the innermost self). Thus the object (mind or universe or waking) is mere illusion on the standpoint of the formless subject (soul).
Man has a firm conviction that he is an individual separate from the world and world existed prior to him and he is born in in it afterwards. This conviction makes him remain in ignorance. And ignorance makes him accept the illusion as reality. Thus he is caught up in the web of illusion experiencing the birth, life, death and the world as reality.
What is this universe (samsara), what is this illusion to the formless soul or consciousness, the innermost self? Consciousness and the universe both are one in essence ultimately. Only people who are stuck to the reality of the universe think the body as body, ego as ego and the world as world. It never strikes to them the waking experience in which they exist along with their world also as unreal as dream.
The dream becomes unreal when waking takes place and the waking becomes unreal when waking entity gets wisdom and realizes it is not the self but the self is the formless witness (soul) of the three states. The consciousness is within the three states as their formless substance and it is apart from the three states as their formless witness. It is apart because it is not and entity or identity within the three states.
The person, who stamped their foot on the ground to refute to show the world, is real, ignore that in dream he would do exactly the same--stamp his dream foot on the ground and assert it to be real.
When wisdom dawns, the soul, the innermost self, wakes up in its formless nondual true nature in the midst of duality (waking). For a Gnani the body, ego and the universe are mere mirage created out of consciousness.
When universe (mind) is considered not different from the consciousness (soul), which is the innermost self, then there is the division of form, time and space. When form, time and space are one in essence than where is the universe (mind).
The universe (waking) is both real and unreal. It is real because it is a manifestation of consciousness, but is unreal, in the sense, that it is not absolute and eternal like consciousness itself.
Many thinkers approach is more practical, and they are stuck with the reality of the universe (waking), they take it as real. Thus they are stuck to the reality of the illusory experience of the birth, life, death and the world as reality. Thus it is necessary to realize the man and the world confronts him are one in essence in order to realize the form, time and space are one in essence.