Maya or illusion is the most important contribution of Sage Sankara.+

The very purpose of analyzing the world confronts one is to realize the form, time and space are merely an illusion created out of the Soul, which is present in the form of consciousness. Thus, to enable one to judge the ‘what is what’ from the highest viewpoint.  

People fail to make this analysis, as with so many religious, yogic and intellectual minded seekers fail to realize the ultimate truth or Brahman because their judgment is based on the waking entity (ego), which is the false self within the false experience.

Sage Sankara says you must first know what is before you. If you cannot know that, what else can you know or understand? If you give up the external world in your inquiry, you cannot get the whole truth.

Until and unless you include the whole universe in your inquiry you will remain in ignorance of the 'Self' which is ' hidden by the universe.  

That is why Sage Sankara said: ~ “Without causing the objective universe to vanish and without knowing the truth of the ‘Self’ how is one to achieve Liberation.

Without realizing the ‘Self’ not you but the Soul, which is hidden by the universe it is impossible to overcome ignorance. Ignorance is the cause of the dualistic illusion. 

The dualistic illusion is present in the form of the universe, therefore, the universe itself is the dualistic illusion or Maya.

Māyā:~

Maya or illusion is the most important contribution of Sage Sankara. Maya or illusion is the complex illusionary power of the Atman (Soul), which present in the form of consciousness. The consciousness is the ultimate reality or Brahman. Ignorance is the cause of experiencing duality as reality. Maya or illusion is present in the form of mind. And the mind is in the form of the universe. And universe appears as waking or dream (duality) and disappears as deep sleep (Nonduality). The waking experience is real from the standpoint of the waking entity (ego). Waking experience is unreal from the standpoint of the formless Soul, the innermost Self.  The shelter of the three states is consciousness (Brahman but consciousness itself is untouched by the profanity of illusion (Maya). Illusion (Maya) is temporary and is destroyed with Self- knowledge or Brahma Gnana or Atma Gnana ". 

One must be receptive and sharp enough to grasp the existence of formless witness which is ever apart from the three states.

Sage Sankara:~ VC~.63: "Without knowing and examining the external world, one can’t know the Truth, as the idea that the external world exists, won't go. It can go only by an inquiry into the nature of the external world.

After verifying through deeper inquiry if one finds the world is the reality within the illusion then he cannot again say the world is not an illusion.

If one is frightened to accept the world is an illusion (waking) then he is unfit to acquire ‘Self’-knowledge or Brahma Gnana or Atma Gnana. Those who stuck with the reality of the world are stuck with the reality of the individual experiences of birth, life, and death, which takes place within the unreal world. Thus the pursuit of truth is for those who have the courage to accept the reality as it is, that is the reality without form, time and space.

When you finally realize the ‘‘Self’ ‘is not you but the ‘‘Self’’ is the Soul then you will realize the world in which you exist is merely an illusion created out of the Soul. The Soul is present in the form of consciousness.

Thus, you, your experience birth, life, death, and the world merely an illusion created out of the consciousness, the consciousness is the ultimate truth or Brahman or God.

The world 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.

People's approach is more practical, and they stuck with the reality of the world, they take it as real. That is why all the confusion. 

In ‘Self’-awareness-- the witness and witnessed are one in essence. That essence is consciousness. There is no second thing exists other than consciousness. 

Thus, whatever seen, known, believed and experienced as a person is a reality within the waking experience (duality) but waking experience (duality) itself is merely an illusion.

Remember:~

A person, who stamped his foot on the ground to refute to show the world, is real, ignore that in the dream he would do exactly the same--stamp his dream foot on the ground and assert it to be real.

All is consciousness.  The whole universe is consciousness. From consciousness, the universe comes. When the universe disappears, the consciousness still remains without form, time and space.

Sage Sankara: ~ “VC~ All this universe which through ignorance appears as of diverse forms, is nothing else but Brahman (Consciousness) which is absolutely free from all the limitations of human thought.

The universe is the product of ignorance. The ignorance is present in the form of the ‘I’.

Sage Sankara says:~ VC-47 All the effects of ignorance, root, and branch, are burnt down by the fire of knowledge, which arises from discrimination between these two—the Self and the non-Self.

Until you think you are an individual separate from the world and the world existed prior to you and you are born in it afterward the ignorance will prevail as a reality. Till ignorance is there the universe prevails as a reality.

Sage Sankara says: ~ “The exercise in discrimination between real and unreal and renunciation of the false is real meditation, then why you are indulging in other types of meditation.

Perfect understanding and realization of ‘what is what’ leads Self-awareness. By holding onto theories one remains in the realm of duality. You have to mentally go on dropping what is not the truth through deeper Self-search. Finally when you become aware of the fact that, your ego, your body, and the world are one in essence then there is Self-awareness in the midst of duality.  

Remember:~  

The universe will not be destroyed,

Some Gurus in the past propagated that the universe would be destroyed if you seek reality, therefore, it is dangerous to seek reality. 

The universe will be destroyed. Only an ignorant will have such an impression.  Nothing is destroyed. Only ignorance disappears and the unreal nature of the universe is exposed.  The universe which appears as waking experience is the dualistic illusion.

A Gnani has the full and firm conviction that everything is consciousness in the midst of dualistic illusion.  The Soul, the ‘Self’ being aware of its true nature in the midst of dualistic illusion is called Self-awareness.   

The universe or the waking experience will not disappear.  It is there always but the unreal nature of the waking experience is exposed in the midst of dualistic illusion through Advaitic wisdom.  

The universe is nothing but an illusion created out of the Soul, which is present in the form of consciousness. 

The whole universe is nothing but the Soul. Therefore, there is no second thing exists other than the Soul, which is present in the form of consciousness. 

It is not as if something that was not consciousness suddenly becomes consciousness. Rather, "knowing the truth” means a removal of ignorance about one's own existence as consciousness. Thus, to "know the truth” is to "be   consciousness." 

Consciousness is ever-present. Without consciousness, the universe ceases to exist.   Consciousness is Self-evident. It is not established by extraneous proofs. It is not possible to deny consciousness because it is the very essence of the one who denies it. Consciousness is the basis of all kinds of knowledge, presuppositions, and proofs. Consciousness is everything. Thus, consciousness is the ultimate truth or Brahman.

The unreal nature of the dream exposed when waking takes place. Similarly, the unreal nature of the waking is exposed when wisdom dawns.   :~Santthosh Kumaar