There is an important difference between being able to exclude stimuli from one's attention and being able to maintain a certain tone or quality of internal state regardless of paying awareness to various stimuli.
The first type of exclusion is similar to absorptive or internal samadhi and may be separate from self-identity and understanding. These absorptions can result from the yogi's or fakir's disciplined concentration or result from a devotee's responsiveness to another's grace. It is also possible to immerse or subdue one's awareness in a drug-induced state. These "forced" oneness states seem to occur in spite of a sense of self-identity or ego. They can be excellent practice for a more complete realization in the same sense that tasting good baklava can be good preparation, almost practice but not quite, for learning to cook good baklava.
In the beginning, one must DO something to experience most samadhis--take drugs, sit and focus, be close to a guru, etc. We use the ego to go beyond ego, we purposefully take action in order to move beyond action. But these actions are still more like tasting than cooking. They use relatively external or obvious or gross techniques to move beyond gross awareness. The individual's experience of more subtle states is tied to the techniques which induce those states in the body.
Over time, there is a shift away from reliance on technique. A shift (well, many shifts) in one's understanding comes with familiarity with subtler states. The subtlety and oneness (and perhaps what Buddhists refer to as sunyata or anatta) fit more and more easily with one's self-identity/experience until there is no gap between experience and oneness. It is natural, and in some sense correct, to identify with the increased subtlety and the shift towards increased subtlety. (As this occurs, many people use transcendental experience to infuse the ego with a spiritual megalomania.)
As the "tone" of oneness begins to stand out/apart from various induced states in one's awareness--meaning: as samadhi is realized to not be tied to technique--the self-apparent and unavoidable reality of nonseparation prevails or assumes a natural priority although not exclusion. In other words, earlier on, the samadhis seem separate from other moments of awareness, special, or ultra-something. While one still may experience moments of intense samadhis or satoris at this degree of realization, the oneness tone of such states is no longer absent during less "intense" moments. To say this again in a different way, samadhi at this level never leaves one's awareness although the multitude of qualities available to consciousness are still available to those who have realized to this degree. (Unless they have traveled a path that emphasizes a particular sort of relinquishment; I do believe it is possible to neurologically burn out or bypass certain responses.)
Pragmatically and eventually, it makes no difference if one's techniques originally emphasized jnana, bhakti, or karma yogas (or other techniques/emphases if you want to list others). Pragmatically, it is best to use techniques suited to one's temperament and situation, but eventually, all paths might be shown to lead to (and be) oneness.
One is thorough or complete in one's realization of oneness, not when this tone permeates one's awareness, but when one is able to express (prepare or cook and serve) nonseparation. How thoroughly does one communicate? Good food is not only a matter of recipes and words, not about flash or presentation alone, not about being a connoisseur. Even if we were all connoisseurs, our specialness or development would go unnoticed without excellent chefs preparing excellent meals. In the same way that it is easier to be a connoisseur than a chef; realization involves preparation and communication; realization is more than being able to taste. This may be seen as the distinction between the degrees of realization I have called Nonconceptuality and Abiding. With Nonconceptuality, one continues to establish the experience of samadhi even if nondual samadhi may be recognized (experienced and understood) as not reliant upon experiencing or experiencers.
While we each may have peak experiences of subtler states without establishing ourselves at more developed stages, we may also have peak moments of communicating or sharing subtle states without being able to communicate the tone of oneness consistently. Communication counts partially because it is possible to withdraw one's attention from external stimuli and remain in an isolated samadhi. While this shows a great degree of talent, there may be little to no wisdom involved, and there may be little to no compassion involved. While it can be true enough that nondual realization does not demand or rely on wisdom or compassion, it does not need withdrawal. So there is a difference between being able to enforce oneness states within one's awareness (sometimes involving withdrawal) and the further ability to communicate or express rather than needing to withdraw attention or exclude stimuli from one's attention. In other words, it is possible to achieve "nondual" states within a dualistic or ego-bound historical chronology but this is not nondual realization. It is nondual experience. The awareness of nonduality is still limited, bound. When one finds one's own way of unbinding nonduality, it unfolds, communicates.
We might be able to more easily come to grips with the difference between oneness and nonduality by recognizing temperamental influences on preferences between various types of states. I am no connoisseur. I generally prefer rustic fare, and I don't want some stuck-up, cosmopolitan asshole telling me what is what. I know what I like, and I am not (perhaps "yet") interested in spending twenty or forty years meditating in a cave high in the mountains, trying to grasp or ungrasp emptiness. But this essay is not apologetic or populist--I greatly appreciate variation, including certain types of elitism. There is simply a great deal of appreciation that can come from recognizing that I am temperamental, that I have these preferences, and that there are signs here of a lack of complete realization. (No, you won't have to look very hard.) But the ways in which we can speak about realization can change if our assumptions about the conversation change. The need for a broad yet accurate common manner of speaking and understanding has been recognized long since. The importance of traditions and lineages has been defended by many, many people. The breadth and clarity of awareness and experience is vast, and we can better--as a group--appreciate that abundance if we see the differences in the light of equanimity and individuality. In Zen, they say that every enlightened disciple or student must go one step beyond their teacher's enlightenment--otherwise they are just reheating left-overs. This expression of the uniqueness of being, quality, and moment does not change when one is just learning to chew, when one is learning to cook, or when one is a world-class chef. If we can greatly appreciate uniqueness in obvious forms, it becomes that much more likely we will appreciate uniqueness in subtle forms.
Copyright 2007 Todd Mertz