To see what conciousness is lets do a simpel experiment in selfinquiry.
Have you ever asked yourself who wakes up in the morning? If you take a close look you may find out that the first one to awake is " I am here" . That is the one who is aware of “I am” realizing his/her existence in this time-space dimension. The second one to wake up is my relationship to the world. It's a person with “my” ideas, concepts and memory”s that give sense and meaning to what I see and experience.
But suppose the second one does not wake up, try to imagine how that would be. Then there is only the awareness of my presence, of my existence. The realisation of me being concious. Still without any interpretation, without and ideas about the world or about myself. In that state of pure presence, is there a difference between “me” being aware and “me” being concious and “me” knowing that I am here? Or are these al the same? And as there still are no thoughts and concepts, there is only perceiving without the mind making up a show. You might say: There is “knowing” without knowing anything.
And you may ask yourself: the one who is awake and looking thrue your eyes, is that the same “me” who woke up yesterday, or 5 years ago? These questions might seem filosofical, but talking about conciousness we have to go back to the simpel and direct experience of " I am" and " I am aware" in a pure sense.
For example, seeing a person walking, you and I may agree that we are looking at the same person. We both are concious of the same human being. But the impression the person makes in your and my experience may be different, depending on our preferences and memory”s.
So “being concious” is the same for both of us, this conciousness is pre-personal. My reaction to what I see may change but than again there is “something” observing my reaction and my feelings. This “conciousness itself” that is perceiving me, is it changing? The old Zen riddle: who was looking through your eyes when you where born? Was it you?
The scientific view
Prof. Jan Koendering is a neurofysicist who is rewarded at many occasions. Here is what he tells about conciousness c.q. awareness.
Why is science unable to deal with awareness? Well, that is because awareness is not an objectively established fact. Sure enough, you have little doubt that you are aware. Science necessarily insists on publicly verifiable facts (so called " third person accounts" ). Awareness obviously fails to qualify, since it is necessarily a " first person account" . Since awareness is a first person fact, its proper study is through phenomenological analysis. Such analysis has been pursued by mystics (not necessarily in a religious context for instance Zen can hardly be typified as " religious" ).
The first thing to notice is that awareness happens to you . There is nothing you can do about it. You do not by any (mental) means control the awarenesses that happen to you. That is why awareness is most aptly described as presentation (vorstellung), rather than as representation. Because awareness cannot be controlled mentally, it is pre-personal and pre-rational.
It is more correct to say " there is awareness" than to say " I have awareness" . The " I" in " I have awareness" only makes sense in the same way as " it" in " it rains" . Did you ever meet the " it" ? (The mystic would ask: " when did you last meet the I" ?)
So awareness is not personal and is not part of your experience. Thus awareness is not temporal. Awareness has no meaning. Meaning is part of thought, and thought is something you do. Thought implies the self. Thought can be true of false, good or evil, and so forth, whereas awareness is beyond such dichotomies. It simply is.
If we look at something there is visual awareness, though there is no one that sees, nor is there something seen. The presentations supply thought with material to work on, visual facts can be manipulated in reflective thought. For instance, you can name objects. When you do so, you are remote from immediate (direct) awareness. This also implies that presentations cannot be illusory, only visual cognition can be illusory in the sense of not being veridical (real or true).
The distinction between visual awareness and visual cognition is absolutely crucial. Visual awareness is beyond truth or falsehood, right or wrong, good or evil, visual awareness is the only visual reality in the strict sense. In the strict sense, all else is illusion, or perhaps delusion. (note: if we strip " visual" you get: awareness is the only reality, all else is illusion or delusion). There are two " visual puns" . First your awareness that works momentarily and second your cognition. The awareness-cognition dichotomy is absolutely fundamental.
The Advaita view
Advaita emphasis that you are not the cause of youself, not the do'er of yourself. This realisation is important to “let go of the person” and come back to “presence”.
Jan Koendering tells it like this:
The scene is experienced with all senses and the recognition and action is automatic, it " just happens" . You have an intention in action for example like walking. But you don”t even know which muscles you use. That is because you don”t initiate the actions. They simply happen. So presentations just happen to you. Good ideas also happen to you , they are not something you do.
An advaita teacher might ask: If thinking is something you do, can you please tell me what your next thougt will be?