You (capital Y) are the whole Infinite Reality (imagined body, imagined appearances, imagined everything n+1). With nothing outside of it, because that would be an imagined arising too. Any boundary separiting IT from an imagined other IT would be an imagined arising, an appearing phenomenon. Infinite.
Try to imagine everything gone, including thinking: NOTHINGNESS. Not big, not small, just NOTHINGNESS. A vast infinite Nothingness, that is not even vast, because there is no 3D-space or anything (no objects/arisings). Similiar to Deep Sleep. YOU are still there. YOU awake every morning after having been there. You already know that you can be totally something/somebody else in dreams, and have totally forgotten all the past you imagine right now to be your "real" human self.
But IT is not Nothingness like nothing there at all, but Nothingness with the POTENTIAL for sentience as soon as anything is imagined, and with Infinite Potential to imagine ANYTHING within it, n+1.
Imagine a water pistol pops up in this Nothingness (see example Massaro, Conversations with a Skepctic):
Then you have a) an imagined appearance (water pistol) and b) "something" perceiving it, the subject.
Or just the perceptions of the water pistal in case no separates self is imagined/arises.
Just the waterpistol perceiving itself, perceptions perceiving themselves. Impersonal.
Then you have a "world", and subject/object.
So what are you then?
a) The Infinite Field with anything that can possibly be imagined? Yes. Nondual/Totality/Oneness. The manifest/imagined side of Infinite Consciousness. Always changing, never stable, since no appearance/form lasts. NONE. But there is a constant:
b) But even more so, you are that Nothingness that can be unaware of itself, Infinite Consciousness initially unaware of itself, but with the potential for sentience if something arises. The unmanifest side of Infinite Consciousness. The unchanging, Unborn and constant core of the True You/Reality itself. So empty that IT is the Abyss, Impersonal. NOTHINGNESS. But also Infinite Potential, since IT can imagine anything.
and "Both"a) and b) is indivisible, nondual. Totally the same essence, ONE Reality. The Nothingness or the True You is already the essence/"substance" of every imagined arisings/phenomenon, including the water pistol, or all separate self arisings (they are all appearances within you).
a nice book about that is Szyper, "Infinite Consciousness"
And that is why with the Big Awakening/Big Enlightenment, you
realize yourself to already be (and ever have been, ever will be) both totally Nothingness (no separate self arisings not transcended or spotted fast enough) and everything manifested/appearing.
Its all One Infinite Reality, imagined in Infinite Consciousness/Mind, hovering empty appearances, hovering in You/Reality, perceptions perceiving themselves. What falls away (or are understood) are just the ignorant separate self arisings, that make you feel and think you are not the Infinite Totality, but this small body "moving" in it. You become Nothing(-ness), but also Everything. No longer a separate body-mind in a larger "universe", but all of that happening in You.
To fully get it, you need
many small awakenings/Kenshos/Enligthenments (becoming gradually the empty infinite mere imagined appearances/nondual field),
and a big awakening (Great Enlightenment, Basis Enlightenment, Great Satori) after you have become the whole infinite empty field, when you wonder who/what PERCEIVES that field. The One Hand clapping.
That is when the last subtle layers of the separate self are suddenly seen through. Sudden Awakening. Its gradual until then, and sudden and unmistakenly with the last shift. Up to that shift, there are stages and higher awakenings. But the bug stops here. That is also why you never know with the smaller Awakenings (1) what the end of the ladder is.... and (2) you still suffer. And of course you can go exploring afterwards, but you already understand what You are and what Reality is when doing that. And how you fooled yourself before, with many different layers (imagined separate self, imagined past, imagined future, imagined anything n+1). The Real You is quite smart to fool itself in such a way.... ( :
Tricky thing with the last shift is:
This last shift needs a fully empty or transended separate self, including very subtle layers of feeling/thinking... And that needs.... a lot of time in these nondual and empty states to get rid of any untranscended separate self arising.
And these last separate self elements can be very tricky & subtle, needing familiarity with them to spot them, and a very fast speed of spotting and transcending/cutting them off in real time.
And: You can't force it here with the usual meditation techniques (that came before this stage) of directing attention. Because who/what is doing the meditation? The separate self.... It has to be automized, so that the meditation does itself. No artificial activity of a separate self. Non-Meditation Yoga in the Mahamudra-System. Or alternatively, but not so efficient: "Bang your head against the wall" for several years with a Koan. That also works, but more brute-force-style and doesn't feel so nice...
Or you win the genetic lottery, jump all of that, find yourself to be the Great Unborn... and have no clue how to get there since you jumped the journey. Ramana-style. The author of these lines wasn't lucky enough to win this lottery. But hey, the point of the ride is ride. Bon voyage! ( :
"We are that reality. When you understand this, you see that you are nothing, and being nothing, you are everything. That is all." Kalu Rinpoche
Selling Water by the River