hi James
yes, by non-dual I mean lack of any sensation regarding self and no selfing
obvious elephant in the room 'the self' can't be there but also more subtle things like body skin tension or sensations regarding if thing I see is mine or not, how I feel, what I want, etc Nothing of the sort can arise, not that you think "I am one with the world" but that nothing like that ever arise in non-duality. Regarding my favourite mu koan you study it and realize that you do not know question and answer is pure bliss because it doesn't matter if that mean yes or no, it doesn't even matter if you have answer or not or that you have question or not. There is only nibbana and mu represent not caring for having it or not, being enlightened or not. Like thought 'I have done it, I am enlightened' is worst thing possible because it push you back and is hurting you so you rather remain ignorant of your own enlightenment status and remain in non-duality.
it does sound kinda ridiculous to be in such mind state all the time in our violent and demanding world and rather too big of a difference between normal dual perception so between dual and non-dual there is intermediate state which is neither dual nor non-dual, hence I named it half-non-dual
there is idea of me but only as aggregate of all the stuff that make up perception and my reaction to things, by which I mean knowledge of causes and their effect to eg. allow or not some sensations. Body's skin tension is almost not felt but instead of total transparency there is this kinda numbed down like one gets from local anesthesia and kinda blurred sensations that do appear. It is not felt as pure selfing but its obvious that it is something that relate to it but not actualized like seeing that from some distance through thick blurring glass that allow only blurred outlines without details. Same with all selfing sensations and self itself. Because of that blurriness it is possible to enter from dual/non-non-dual to this half-dual/half-non-dual mode relatively easy compared to sharp difference between dual and non-dual, kinda like with shift stick cars you do not start with eg. 4rd gear but you have to build momentum first on lower gears. Also with this half-non-dual perception what is important stuff you see that is not you is partially you, part of you, seen as indifferent from you and you indifferent from reality around you. What make it not full is that in full non-duality there is not even slightest idea about you and not you hence idea of being with reality does not arise either. But if thought 'I am exactly what?' arise you do not counter it with 'I am all the things in universe!' or something like that which would make just another version of subtle duality but you mark it as dual and unskillful loaded question and refuse to answer it. Just not worry if mind gets irritated several dozen thousandths times at first, the point is to unlearn to ask stupid and ignorant question and not to find answer.
general advice for anyone who haven't experienced non-dual more deeply and have issues to go there is that final goal should be final goal but intermediate goal were main focus until they are mastered and one of those intermediate goal is mastering half-non-duality that is like good foundation and main body of work is done there. Its there where one actually practice Noble Eightfold Path by which I mean choosing to allow or deny sensations from arising and if they arise stopping them. And one have to stop all stuff that describe him/her so its dirty work with a lot of hard choices. Thankfully as it seems there is no need to do like most spiritual masters advice to throw those babies with bathwater and instead all is necessary to throw bathwater. As I always said, desire is aggregate of skillful and unskillful sensations. It is possible to feel oneness with object of desire without suffering of not having it. In dual perception mode one can't really do any of these things like that so it is necessary to first get to stable ground of partial non-duality. In dual perception desire hit and it hit hard because it hits both mind and body, it create tension in your skin, in your muscles. How can you stop tension in your muscles? You can't and because of that you have to not feel them is such way in the first place.
I kinda get what you mean by 'inkling' and my advice would be to mix it with duality, with self. Its impossible for you to jump from dual to non-dual directly. You will only feel irritation from trying it. You have to merge those sensations of dual and non-dual into one.
Try to feel duality and non-duality at once without any flickering back and forth, that should do the trick and open your way to half-non-duality like it did for me. I had the same issue, I tried to enter non-dual directly from duality and while it was not complete failure it is now considered by me to be unskillful way to do that that made me needlessly suffer. Well, there was probably benefit from practicing that but true change came with attainment of proper half-non-dual mode. There is even topic about that
URL. Just mind that my then 'full non-dual' is nowhere near my current full-non-dual perception and realization that topic is about is what I call half-non-dual now. My no-self mode then was one of important ingredients of non-duality but not really what I call non-duality now. In no-self there were a lot of question, answers were just hard to find or pointed to non-existence, to fact that things like my own body movement is doing itself. In non-duality as I have it now there are no such questions, I just couldn't care less, and if one do arise (which is act of unskillfulness) I can answer 'mu' and be done with it. In half-non-duality there is answer to those questions but compared to 'mu' its just dry burnt and bitter toast. Still it is better to know those things to not ask those questions anymore.
ps. sry for wall-of-text above ;)
ps2. you probably already had half-non-dual state at some point in your life, as a kid for example. It is nothing out of ordinary. Its us who complicated those things with our ignorance and unskillful ideas. Imho many people never really fall down to state of self, they instinctively avoid dwelling in self based stuff too much. So technically it is nothing out of ordinary. Though there is difference between it being attainment and just natural state and it is in reliability and not falling from it. People even when are >90% in half-non-dual still easily fall to non-non-dual, are too dependent on conditions. Non-duality practitioner that have similar mind state as people around him differs in that he won't fall off this bull when there is some disturbance and this is what make main body of difference. Maybe after some time its possible to not fall even from full-non-dual but that for now is only speculation and its not like I even care bout that. I was caring about that I wouldn't be able to hit full-non-dual at all. I can't worry about any state being there for me or else I fall into duality and suffer. Feel where it is heading?
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ps3. I should also note that this realization is not really even touching Three Characteristic or 'blips'. It skips all that entirely. 3C is such a dual idea anyway as eg. for impermanence there should be permanence and the point is to not ask question about permanence of things at all and not having any answer for those unasked question either. It doesn't matter if sensation is permanent or not if you do not allow yourself to desire it or cling or get away to it to the point that mind does not desire anything or cling or use aversion toward anything. In full-non-dual ideas like impermanence, non-satisfactoriness and no-self of sensations do not arise, ideas of being, of sensations, of emptiness, etc they all do not arise. Mind abides in nothing at all. If anything arise then it is not full-non-dual but half-non-dual, mind has fallen out of nibbana and one is not really enlightened anymore