Non-duality—or whatever it is called, by whatever tradition—manifests in all traditions everywhere and at all times. Out of realization of non-duality, all benefit appears: in every language and land, whatever is needed, in whatever form is presented, accommodation to that form is effortless, spontaneous. In this culture and time, it may be one thing; in another culture and time, it may be another.
The non-dual view, as it is sometimes called, is not an accomplishment. It is no accomplishment to see what is as what is. (Akin to seeing and then announcing to all around you, excitedly, “The sky is blue! The sky is blue!”)
For example, if we agree that the space between us is a wall and one of us were to put our arm through the wall and touch the other, would we think this a great accomplishment? Why not? Because there is no wall. But supposing, deluded, we all, or any of us, thought there were a wall? Imagine how it looks to a fish in a pond (say one of those intelligent Japanese Coi), your standing over it, looking in, while the fish looks out. To the fish, you appear to exist in an alien environment, for one, and for another, the surface of the water is impenetrable, impermeable to life as the fish knows life. In fact, the same water is quite permeable to you. You can enter, even swim around in the pond with the fish, but the fish cannot go beyond that wall. To the fish, your activity, which is effortless--you think nothing of it--is a miracle at best, but more likely than not, “beyond” comprehension.
A classic example is given of the tea cup and space. The space inside the cup and outside the cup are the same space. The cup does not divide space. The continuity of space is not divided by the cup. The cup does not harm space by “cleaving it in two,” but is in fact inseparable from space. It is only our attachment to the cup as dividing space in two that is the cause of our duality about space inside or outside the cup. There is really nothing wrong with the cup in all this. It’s a perfectly good cup’handy for drinking tea—and there is no need to smash it. The only thing we need to break is our attachment to the cup as breaking up the space, our mind, our selves and the world. The cup is not the problem. Only our view of it is.
This is easier explained than experienced. Why? Very simply, because non-duality, experiential non-duality, terrifies us, as Plato meant, in the “Myth of the Cave” (from the Republic) when he said, “it is normal for young children to be afraid of the dark; the tragedy is that adults are afraid of the light.” Or as a Buddhist teacher put it, paraphrasing, “we think we are afraid of our darkness, when in fact we are afraid of our light.” As Buddha said, we are insane because we take the real to be unreal and the unreal to be real—in other words, we have it all backwards.
Duality should terrify us, instead, we pay it no heed—it’s as though our hair were on fire and yet we felt "reasonably okay, thank you"—this was another of the Buddha’s examples. Contra wise (that is, "insanely"), non-duality is too scary for words--perhaps that’s why genuine realization is said to be "ineffable." We are quite afraid of Truth--that will set us free, to see, as we, as anyone at anytime, anywhere can see, that between good and bad, atman and non-atman, there is no duality, between Christian and Jew, Buddhist and Hindu, Muslim and Atheist, between Black and White, Male and Female, Rich and Poor, Mahatma Ghandi and Saddam Hussein--now that’s terrifying! We would rather be comfortable with our dualities—however uncomfortable our experience of them, the devil you know (duality) versus the devil you don’t, as we perceive non-duality.
It takes great courage to find a path to non-duality and to practice that path—any such path, regardless of what name it is known by or who teaches it, or where they/it comes from, knowing at the outset that you will meet, engage and defeat the enemy—the dualities within you and without you—thinking all the while (and feeling) that those dualities are you and you are they. Funny, in a way, that the Hindu tradition describes non-duality just so: “tat tvam asi”—thou art that.
Now (as any) would be a good time for each of us to find a path for all of our sakes. Choose and try, and choose again, and choose again, if necessary. One can hardly miss, if one but try.