Upanishads says:- What use are the scriptures to anyone Who knows not the one source from whom they come, In whom all gods and worlds abide? Only those who realize him as ever present within the heart attain abiding joy. - Shvetashvatara Upanishad
Everyone is seeking eternal peace, and misery is most unwelcome to all creatures. Every living creature is engaged in some activity or the other only in search of eternal peace. But they have not attained this peace because they are not aware of their formless true identity. Instead they have gotten themselves entangled only in pain and pleasure because they are not aware of the fact that, the self is not form but the self is formless. They have not been able to get this non-dual peace because they seek physical happiness from external objects, while the truth is that non-dual peace is within the mind and the search must be made within to attain this supreme peace, by investigating what is mind and what is the substance of the mind.
All the pleasures that are derived from the world are trifles compared to that non-dual peace which is the Supreme. Hence, it would the greatest help if one could show the way to this eternal peace. The Self-Knowledge is the tool to non-dual peace which is the nature of the true self, which is in the form of consciousness.
In self-awareness there is complete cessation of sense “I am the doer ", "the objects that are seen or perceived are not different from the soul, which is present in the form of consciousness", so on and so forth. In self-awareness there is no misery or delusion.
There is a delusion or misery for the one who has realized this non-dualistic or Advaitic truth. “Because he is fully aware the experience is a mere mirage created out of consciousness. Thus man and his universe are mere experience within the mirage. In self-awareness there is no mirage only non-dualistic reality.
The mixture of pain and pleasure is inevitable to all beings that are born within the illusion, which is in the form of the universe. Till a man thinks he is the doer he is action oriented. In the realm of action he thinks he is an individual separate from the world. As an individual he has the conviction that, he is born in this world and the world existed prior to him. Till this conviction is there it is very difficult to grasp the non-dualistic or Advaitic truth.
Deeper self-search reveals the fact that, the self is not the form (waking entity or ego) but formless (soul or consciousness). Therefore, if the self is formless, then, one which is born, lives and dies is not the self. If the self is birth-less than whatever seen, known, believed, experienced on the base of birth entity is mere myth. Thus the birth entity and its experience of the world is myth. Hence the world where the birth, life and death takes place is a myth.
The universe which is present in the form of mind comes and goes as waking or dream is unreal on the standpoint of the soul the innermost self, which is present in the form of consciousness. The substance and witness of the mind, which is present in the form of the universe is consciousness. Since, the formless substance and witness are one in essence there is no scope for existence for second thing. Hence it is non-dual. Thus consciousness alone is real all else is mere mirage created out of consciousness.
As long as one believes the body as self, he is bound to believe his body as the doer. Till he thinks the body as the doer, he is bound to believe that, birth life, death and the world as reality. Till he believes the birth, life and death as reality he is bound to experience the illusion as reality. Without the consciousness the body and the world cease to exist.
The birth, life, death and universe are reality within the waking or dream. The waking or dream is unreal on the base of the true self, which is consciousness.
Hence if one wishes to overcome the experience of birth, life, death and the universe (illusion), he has to realize the fact that, the self is not physical but the self is formless soul,which is present in the form of consciousness.
This awareness of the soul without physicality is possible for the individual only if the root cause for the ignorance is completely destroyed. Ignorance arises only if one sees the objects of the world as external to him. If there is no second object other than consciousness, then there is no room for any ignorance at all! Absence of ignorance leads helps one to overcome the illusory cycle of birth, life and death. Once the soul, the innermost self is out of this illusory cycle, there is no scope for experiencing the illusion as reality. Hence this self-awareness is known as "Liberation" or “freedom”.
To get freed from illusory reality, following the same track, one must get rid of the 'Notion of diversity' which is the root cause of experiencing the illusion as reality. This is the road to non-dual peace, which is the nature of the true self.
How does one know that, there is no diversity at all, when we have the cognition of this entire universe with all varieties in its creation?
The truth which is the soul or consciousness is the only reality and that the apparent notion of diversity (the root cause of all miseries) is only due to ignorance. If this ignorance is destroyed once then the knowledge of the soul, the innermost self arises, then one becomes fully aware of the fact that the consciousness is ultimate truth.
Once this self- knowledge arises, one is able to disconnect identity with the ego(waking entity) and identify with the soul, the innermost self, which is present in the form of the consciousness. Thus consciousness is the ultimate reality or Brahman.