Soul-centric reasoning is necessary to unfold the mystery of the mind or universe.

One remembers a dream after it has passed. He does not remember it as a waking experience, but only as a dream. In the dream, if he were expected to remember waking experience it should similarly be remembered as a dream and not as a waking experience. In dream one has his food, body, hands, car etc. This proves that what was known in waking reappears in dream, where again it seems real. How could he recognize cake in his dream, unless he had previously seen it in waking? Thus the waking entity is not the knower of the whole waking experience. The knower is the one which knows the waking/dream/deep sleep experience as a whole.

 This is the reply to the objection that one cannot remember waking life in dream, although he remembers dreams in waking.

The soul or consciousness, the innermost self   witnesses the picture of the waking world and converts sensation into its own images. It is the same as in dream, where it creates its own dream world that exists within it.

 The conscious inquiry into the nature of the objective world during the waking experience gradually brings about a "waking up" during the dream experience and one begins to realize that one is dreaming. That means that if one sees an animal during his dream, he will understand quite well that the tiger is only his idea, or dream. But this condition will arise only after the mind has saturated itself with inquiry and discrimination during waking experience.

How is dreamless sleep known? No waking  or dream were present then. Hence it is only known by negation of the duality as a whole; in the same way the pure self is also only known by negation.  The gap between two experiences which appears and disappears is equivalent to the deep sleep state.  The knower of the all the dual (waking or dream) and non dual (deep sleep) is formless non dual and eternal.  

Deep sleep and the dream are ever present with us, but the idea of time prevents us from apprehending them, for it makes one think that such and such a thing has ended and so on.

Soul-centric reasoning  is necessary to unfold the mystery of the mind or universe. one has to inquire   into the the world facing him, before he can understand the truth of their reality. The presence of objective world is known only in terms of their absence that is the color black is known as black only in terms of contrast with the color white. Hence Reality is to be known only as distinguished from unreality. In deep sleep the entire waking or dream disappears from consciousness, that is, becomes unreal. Therefore, the different experiences are really relative to each other. In realm of truth when the one becomes aware of Reality there is no distinction between the three states.