There seems to be a simple progression from I as seen, then as seeing, and then absent.
I as seen
First, there is a belief in the idea of I and it is placed on content of awareness. More specifically, it is placed on this human self or aspects of this human self, those aspects that fit our identity, our beliefs of what or who we are as a human being.
This human self and the rest of the world arises in awareness, and this is filtered so that this human self appears as I and the rest of the world appears as Other.
In this process, awareness itself may appear as Other, as something that comes and goes, that there is more or less of, that can be distracted. I am this human self, an object in the world of phenomena, arising within space and time, subject to birth and death, and awareness is somehow an appendix to this human self, a property of this human self, and it can be more or less present.
The center of gravity is mainly in the seen, in our human self.
I as seeing
Then, the sense of I shifts to awareness itself, to pure seeing, to witness, to this clear awakeness.
I am awareness, and the whole world of phenomena arises within me. I am timeless and spaceless, and time and space arises within me. I am without form, and form arises to and within me. I am seeing, and Other is the seen.
There is a tremendous sense of liberation in this. There is a disidentification with the human self, with its reactivity, limited identity, precariousness and mortality. The world of form, the world of phenomena, is revealed as a seamless whole. There is no inside and outside anymore.
The center of gravity is mainly in the seeing itself.
Finally, there is the dawning realization that here too, there is a sense of I and Other, and where is really the dividing line? What is more true in immediate awareness? Is there an I and Other? How can there really be an I and Other here?
I as absent: Spirit as seeing and seen
As this is explored, there is the realization that any sense of I and Other comes from the belief in the idea of I, placed on the seen - this human self, or the seeing itself.
Now, seeing and seen is revealed as inherently and always absent of any I. It is all Ground in its many appearances. It is all Spirit. It is emptiness dancing. It is the Divine Mind, revealed as seeing and seen. The seen is no different from the seeing.
The center of gravity is now in Ground, appearing as seeing and seen.
Each of these shifts are clear and significantly different from each other. Yet, there is also often a gradual shift in each case. There may be glimpses of the next phase, temporary shifts into it, intuitions about how it is, a sense of how it is. Then, there is a more clear shift into it.
For instance, when there is still a sense of I placed on the seeing itself, there may be a very clear sense of it all being one, that the seeing and seen is Spirit, that I and Other is no different. But this is still merely a sense of it. It has not yet shifted into a clear, obvious, indisputable realization that seeing and seen is inherently absent of any I whatsoever. The center of gravity is still mainly in the seeing and has not yet shifted into Ground.
And when this shift occurs, it is seen how filtered the previous realization was, how much there was still a sense of I there, even if it appeared quite transparent at the time.