So, I've heard this several times, if there was a wall, and somehow you imagined/hallucinated it to be gone, and you didn't see it, then would other people see it? Or is it only a hallucination?
Well, I tie this one in with the body.
Sometimes, we're inside our body, we ARE our body.
But if you think about it(I also covered this in Volume 002)
That if you look in a mirror, for a split second, it might seem like you're OUTSIDE of your body. Like you aren't looking at YOU, but just a body you're trapped in.
So then, sometimes we're so in our head that we forget that's it's OUR body.
I think it can go the opposite way too, when we're so caught up in our bodies that we forget we have an actual mind.
So, in a way, the body acts as the wall.
You sometimes hallucinate it isn't there, but it is. You might be blind to something or how you look, or what you are even, but everyone else can see you. Your body. The wall.