Kenneth,
thanks for the definition. glad that you clarified this because we'll just end up in circles without proper context.
in my posts on this thread, my context has always been your definition #2.
"2. To go upstream, to the source, before the split occurs (my favorite)."
this is similar to going back to simplicity. meaning, this is a process of "reduction". the reason i prefer this perspective is that it is the same approach of objective science and theoretical physics (e.g. reduction from cells, to molecules, to atoms, to quantum packets, strings, and who knows what). if we go in the other direction, then it becomes a "transcend and include" context.
in theoretical physics, a theory of "everything" is an equation which could fully explain and link together all known physical phenomena. so far, we've got M-Theory (or string theory) as the prime candidate (good luck with that

) for physicists this is the description of the nature of physical (or objective)reality, whether we agree with them or not. on my part, i prefer to riff in parallel with the scientific context of reality. hence, my previous posts.
this is the reason why i like vipassana because it is science-like. it's a process of (subjective) reduction: reduction of sensory phenomena into their separate components (touch, sight, sound, feel, etc...). when viewed this way, then what is the best description of ultimate reality then? (for sure it's not an elegant mathematical equation

) Shinzen Young describes it as the polarity of (positive and negative) "waves" canceling each other out: "the zero" which is nothing but contains everything. now, you guys tell me what corresponds to this in the Theravada developmental map

~C