I failed to mention that I am a full-time psychotherapist and am telling you now to make you aware that psychobabble bullshit may be coming your way!
No one is thinking the "I" thought because no one as controller/protector exists. The "I" seems to have become self-arising and self-sufficient. Since word thoughts, image thoughts, emotions and memories are directly or indirectly connected and interconnected in an intricate web, it only takes one of those internal experiences and "I" has all it needs to build itself, especially because we do not have any control over the initial thought, feeling or memory.Who is thinking this I-thought?
We do have a say in whether or not we'll attach ourselves to that initial thought or be averse to it; either way attachment or aversion are both acceptable fuel for the "I".
In the continuous letting go of internal experiences that appear, there is still the false-self's propensity to gather these thoughts/feelings to reconstruct itself. "I" is sneaky and when letting thoughts come and go, one should be mindful of the ego's magnetic abilities to gather them all and build the false-self. So letting go of control and allowing everything to be as it is, as beautiful as it sounds, only allows the habitual false-self to self-arise and self-sustain.
Pure Awareness, Consciousness or the other various names that have been given to it. This awareness is the thread of continuity that has been with us since birth. This is the context in which our lives unfold and not the contents that the false-self so badly needs! It is the same awareness that has been watching every single thing that we've been through and yet has been unaffected. It simply watches without bias or judgment.Who is noticing the I-thought?
All the best,
Mark

