Deep Sleep is a key to understand the ultimate truth

Deep sleep brings on a sense of object-less peace with it. This experience one gets only in the absence of mind, which is in the form of universe. When one focuses his attention consciously on the formless witness of the three states then which wards of the mind or duality or illusion [waking or dream].

So, one gets to the real nature of the soul or consciousness by focusing the attention on the formless witness, consciously and at the same time by being aware of the body and the universe and know them consciously as consciousness alone.

Once one becomes fully aware of the fact that whatever exists as object (body + universe) with form or shape are also consciousness because they are made of consciousness. 

Thus, deep sleep illustration can be utilized the real nature of the soul or consciousness, which is   without duality (forms and shapes). Realizing the truth of the true existence   in the midst of waking experience is Self -Realization. 

There was no mind is deep sleep. As soon as waking takes place the mind which contains, of a ready-made universe – including all men and creatures appears. The man – confronts universe in waking or dream. The waking or dream appears as a whole and disappears as a whole.  To examine it closely, one has to analyze the three states and trace the witness of the three states is formless and apart. 

One becomes aware of the fact that, the universe or mind, which appears  as waking or dream and disappears deep sleep. All  form and shape within the waking experience  are  created out of consciousness and nothing else. all the forms and shapes disappear as deep sleep.   That is form becomes formless or mind becomes soul.

The consciousness alone is positive proof and on the standpoint of the consciousness or soul as self, one becomes aware of the   falsity of this universe or mind, which is mere appearance. The one which appears as mind (universe) and disappears as no mind (soul) is consciousness alone. Therefore, the mind and soul are one in essence. 

Mental analysis shows that, the existences of the formless witness, which witnesses the three states coming and going without a break. This, on closer analysis, is found to be that changeless, soul or consciousness itself.