Dattatreya's Song of the Avadhut 1.36-42:- Non-duality is taught by some; some others teach duality. They don't understand that the all-pervading Reality is beyond both duality and non-duality.
Not by intellectual speculation but only by an awakening to the reality of his true existence he gets soulcentric vision. Soul, the innermost self’s nature is like state of deep sleep.
No one has ever seen the coming and going of the universe, which is in the form of the mind, because he exists within the universe. All individual experiences happen within the universe, which is mind. The mind or universe appears as waking or dream and disappear as deep sleep. The formless substance of the universe or mind is always present in all the three states. Cities and people may multiply in one’s dream, but the mind itself does not therefore increase or gain. Yet the cities and people are none other than the Mind-Stuff itself. Thus universe or mind is mere illusion on the standpoint of the formless substance, which is consciousness.
When one regards three states as an object, then he must know that there is a formless subject which sees or knows them. In this sense only do we think of the formless witness. Hence object is a necessity in order to point to the existence of the formless witness. When one does not regard objects as objects he loses the knowledge that there is a formless subject.
People cannot think of the Mind without some object, thought etc. contained in it; they cannot believe in consciousness apart from the contents of consciousness. People regard objects only as material. One has to regard the thoughts and experience also as part of the object, because they are part of the three states, which are an object to the formless subject.
The ignorant have no idea of a subject and hence never seeks for it.
Only by discrimination between real and unreal mentally the truth will be revealed. It means separating subject from object mentally.
Being means a thing is. How does one know his body and the universe exist? How does he know about his thoughts? It is the witness that gives him the idea of being but he is unaware of the fact that the he exists within the universe and his thoughts and his individual experiences are happening within the universe, which is an object to the formless subject.
Scientists think only of the universe and they think man is the subject and everything else is an object; the thought that such a thing as the formless witness also exists never strikes them.
One has to give up whatever object, idea or thought he has, and then only he realizes the ultimate truth. When one gives up the mind or the universe ('I') he gets non-dualistic or Advaitic truth. One has to detach mentally from the mind or universe by realizing the formless witness is the true self, which is in the form of consciousness.