Sage Sri Ramana Maharishi Says: The self is fullness of consciousness. Therefore, there is nothing apart from it. (Page-8 – Practical Guide To Know Yourself).
Waking and dream emerge from consciousness. The emergence of the waking or dreams does not make any difference to the consciousness. The consciousness remains unchanged and unaffected by the waking or dream, even though both the waking or dream objects and the waking or dreams are aspects of the consciousness.
The dreamer would not realize that dream objects and the dreams are simply aspects of the consciousness unless he wakes up from the dream. Once the waking takes place the dream becomes unreal, same way when wisdom dawns the waking becomes unreal. The unchanging reality behind the waking or dream experience is the consciousness.
Consciousness (soul) is the substance and witness of the duality. The duality is present in the form of mind. Mind is present in the form of universe. The universe appears as waking or dream and diapers as deep sleep. The one which is aware of the coming and going of the three states is neither the waking entity nor the dream entity but the formless soul, which is present in the form of consciousness. When the soul becomes aware of its formless non-dual true nature in the midst of duality it is called self –awareness. It is foolish to limit the consciousness only to duality because the consciousness pervades all the three states
The waking or dream experiences are external manifestation of consciousness. As long as a person is caught up in the phenomenal existence, he does not see the unity behind the multiplicity. When one wakes up to the consciousness as it is in itself, not perceived or interpreted, or noumenal level he becomes aware of the one, non-dual consciousness, which was the cause of the three states.
Thus, consciousness is supreme. It is the reality. It has no beginning and end. It is eternal and beyond the reach of pain and pleasure. Consciousness is indivisible, immeasurable, without names and forms. It cannot be avoided, as it is present everywhere. Consciousness cannot be grasped, as it is transcendent. It cannot be contained in anything, as it contains everything. Consciousness is indefinable, for it is beyond the range of action and speech. Thus, consciousness is reality itself, pure and absolute consciousness.
Consciousness is ultimate reality is defined as that which persists. Consciousness exists in all periods of time and remains the same in the past, present and future.
Consciousness is ultimate reality exists both in the manifest and the unmanifested. The mind, which is in the form of universe arises out of the consciousness .The consciousness exists in all the three states. The mind rises from it and Merges back into consciousness.
Consciousness is the substratum and the three states. Consciousness is like the ocean and mind is like wave. Wave exists in ocean and Merges back into ocean. Similarly the mind or universe is nothing but consciousness. Everything is consciousness.
Therefore, consciousness is a principle of utter simplicity. There is no duality in consciousness for no qualities are found in the concept of consciousness. It is also simple in the sense that it is not subject to inner contradictions, which would make it changeable and transitory. To understand the nature of consciousness and to speak of it, consciousness in its reality, is not a metaphysical postulate that can be proved logically, but it must be grasped and realized mentally not through argument or logical conclusions but perfect reasoning. Thus, consciousness is one: It is not a `He or She ', a personal being; nor is it an `It', an impersonal concept. It is that state which comes about when all subject-object distinctions are obliterated.