The impossibility, and the necessary inadequacy resulting therefrom, need to remain an important part of the conversation; of the contemplation.
Think of something--a mushroom.
A mushroom. Mushroom. Think of a mushroom. Something you pick? A slice you eat? A plastic-bottomed pack of them in the store? An unwanted or unexpected toadstool on a walk?
A mushroom with a shape and a (sic) size. Just an imagined mushroom inspired by a sentence on the internet. Now, think of it not existing. Now think of it never having existed--this part of the internet is gone, we go back in time with those rules, and so you never saw that sentence and never thought of that mushroom. Hard to do, so imagine a team of cruel neurosurgeons grabs you and cuts out that experience, has the components disposed of, and are themselves then operated on so they no longer remember what they removed or who hired them to do it. The crew who performed the second surgeries doesn't know why, and once they're assassinated in secret two days later after only moderated conversations during which they were confirmed not to have mentioned anything about a reasoning behind their actions by a single suicidal assassin who eliminated them and then took his own life, any possible reference to that mushroom-thought, or what may have inspired it, let alone you yourself, is gone. Completely, totally, utterly gone, forgotten and unsung.
Now, did that mushroom ever exist? Was that thought ever thought? Yeah, something motivated that medical assassin squad, so it existed even if we don't remember it, so take out the said squad and just assume it was a mild mental hiccup that didn't really mean anything and then fast forward ten years and you've never mentioned it to anyone and you never thought of it and it's just as gone.
The requirement of removing the assassin squad implies that an impartial observer can still remember that something happened if it had even seemingly-unrelated but actually-related effects on time, so transmaterial, transtemporal scenarios work best here; the memory is never spoken of and simply lost.
So, did that imagined mushroom, that thought, ever exist, once the assassination squad and/or normal forgetfulness of unimportant things do its work? Do any memories, once forgotten, exist in the sense that they have happened? Faster-than-lightspeed travel is ruled impossible, or wasteful, or dangerous by future Earthlings, so we colonize only the solar system and enjoy a few million years and then a few of us finally set off during the annoying, depressing times of the red giant, and then the ship crashes anyway. In the meantime, our civilization has generated quantity X of total memories, but the red giant consumes all the scraps of material conduit and shifting gravity in the area pulls the remains of the crash back (or it just got lost along the way and everyone starved, jeez), and everything that was here is gone. Or maybe there's a "Big Crunch" and everything that was what we think of as everywhere is gone, so same effect but on more of a scale of what we'd imagine as totality. Gone; done; finito. And if there was ever someone in that space who imagined an inviolable interdimensional server, that person and their inaccessible thoughts are also as gone as all the rest of the stuff.
All forms, in the same way, of the ineternal conundrum, whereby we can question whether something has ever existed "once" it doesn't exist. All important, in the sense through which we use it to think about whether reality can or does exist. It's easy to conclude that we exist now, but might not later, so there is no contradiction, but if we understand time, we understand that the ability to delete everything is the ability to delete everything, ergo cesspooling all material reality means that anything it might've done not only doesn't exist, but never existed. And that's supposed to be our trapdoor to eternity, in the sense that any memory, any perception that recognizes it is a perception, makes ineternity impossible; requires eternity. Which can be a form of relief.
Did the mushroom exist? Did anyone ever read an essay in which that one was prompted to imagine a mushroom? Explaining this is a tautology, like explaining that "something is red because it's red," where all the fields in the folder are user-defined, and it's a bit ridiculous to say "because it is" over and over, completely illogical and often arrogantly misemployed now, like saying "Risen Rabbi loves you because He does" somehow makes it true. No, if we're going to be smarter than that, we have to know why the mushroom still existed; why some kind of transcendental error-free storage space, as we might think of it now, does or can or must exist. And that's the conundrum; and that's what brings us to lazy "faith" over and over again, where we admit we're not smart enough to know but really really want to know.
There are all sorts of fractals and brief misunderstandings that can bring us there, even with the crippled little brains we have. Better brains can recognize these answers the same way we can recognize "red," as a tautological explanation where we can see, like magic, what's there. And sticky impressions can do their thing; the wise man in the clouds, or the Risen Rabbi, can sort of do that, with the relevant figure as a stand-in for feelings of peace or acceptance or love or "don't worry mon" that are associated with a retrograde perspective on being here compared to somewhere else. So, no matter how many lost con artists and deluded hopers one finds, one can still recognize goodness in the blurred shreds of anything perceived; anything remembers. The color "red" exists because we define it, and also because a certain quanta of light energy gets arranged in a certain way, and even if we were trying to lie, even if we have a different language or no language or no one sees the tree fall in the forest, the light has still happened and the tree has still made a sound in the way we were trying to refer to that sound, in the way that the shifting of that material against other material has produced sound waves, even if no ears exist near enough to it to hear it fall.
Realizing you exist is sort of an eternal victory, because if at any point/unpoint ever ineternity, nothingness, had controlled anything, it would un-be a comprehensive wipe of everything, including your having been able to frown at this sentence and/or ever remember, even for one nanosecond, having so read that sentence, having seen a computer, taken a breath, et cetera: all deleted when a total nothing is possible. So no nothing is ever possible; the battle is already over. It has to be not because it's reassuring or beautiful or any of that horseshit, but because it's the most boring aspect of mathematics or logic one can imagine, namely, that nothing can't ever unexist/exist because one tiny shred of existence means existence has already won forever. Time, like material, like energy, perpetually grows, and can never end or reverse its growth because if it ever had or could, that reversal would already have eaten up whatever happened a second ago or will happen a second from now.