Atma Vichara & Neti Neti
When I first was given the inquiry (or koan) Who or what am I? by a Zen teacher, I went at it with a great deal of energy, effort and a sense of struggle and wanting to "break through". Now, it seems much simpler.
It seems that one key is to combine the inquiry with Neti Neti - not this, not that.
Whatever I see as a form or object - belongs to the manifest world. And whenever something appears as an object, it is not the subject. Whenever something is experienced, it is not the experiencer. So this is a continual process of peeling off, of recognizing what appeared as a subject now as an object. And a continual revisiting this until it becomes blatantly obvious in daily life and more and more situations.
For me, I find it useful to look for what appears most as "me" - which is often particular thoughts, emotions and reactions - and then recognize this too as an object. It is no different from the tree out there, the sky, the clouds, a chair, other beings, etc. This too, belongs to the world of forms, the manifest world of innumerable objects. I can do this as a more dedicated practice (for instance while sitting in meditation or lying down), or in daily life as it happens - as things come up that I have a habitual tendency to take for "me".
I continually bring what appeared as a subject into the realm of objects, and what is left is just the experiencing different from the experienced.
And this experiencing now appears as me.
Identity as Witness
I now find myself as this pure formless awareness, with no center anywhere, choiceless, Unborn, the Original Face, impartial, the stainless mirror perfectly reflecting anything arising in the present. As that which is distinct from the world of phenomena and beyond any characteristics or words, including these. As that which is empty of characteristics, forms, sounds, tastes, smells, sensations, and yet perfectly and effortlessly reflects and receives any and all characteristics, forms, sounds, tastes, smells, sensations as they happen in the present. As the emptiness full of the world. As capacity for the world.
There is often a phase of this continually peeling off, of gradually shifting the center of gravity to the experiencer and of finding ourselves in more and more situations as the Witness.
Deepening into recognizing the I vs. other dynamic
And then we may apply this continual realization of apparent subjects revealed as objects. If all these that I previously took for "me" turned out to really arise as forms and objects in me, then isn't this new "me" - this Witness - also just an illusion of "me"? We realize that whenever there is an apparent "I", we create a sense of "I" vs "other".
We split the natural wholeness of Existence into "I and other", into experiencer ("I") and experienced ("other"), and this is just another way of believing in the thought "I". It is another way of believing in an overlay of abstractions, instead of just being what is. It is another way of creating an apparent split where there is none. Another way of misaligning our view with that of Existence as it is.
We create a subtle duality where there is a naturally more deeply transdual view available, one that inherently embraces all polarities - as Existence does.
As we recognize this, the last attachment to the thought "I" erodes and just reveals what is, as it is.
No I anywhere
The content is still the same. Clouds, sky, trees, smells, the cool breeze, the computer, the walls, the floor, the taste of apple, the sensations of the body, the emotions, thoughts, reactions, behaviors, pure awareness. But there is no "I" to be found anywhere here. It all arises as a field, not arbitrarily divided into "I" and "other".
And there is a great sense of freedom and fullness in this. Of it being just as it is, effortlessly, naturally, inherently. Of just resting as what is, as it is.
It is just Existence manifesting - as it does on its own - without a belief in the thought "I".