It takes a second step of self-awareness, in my thinking, to go beyond realizing that you exist, to realizing that just because you think you know you exist, doesn't mean everything you think exists.
Oy, now my head hurts!
In many ways, if we want to function on some level, we have to accept that preception is our reality. If we can't accept that, then what have we got? On the other hand, I like to think that I really know somewhere between very little and nothing. Therefore, no matter how much I know, there are worlds and more out there.
My reality? It floats somewhere between "here I am, and this moment and this place are all I've got to work with" to something along the lines of "Horton Hears A Who". Who can say with certainty that we are not part of a galaxy in a universe that floats around in a dust bunny in the corner of a cottage, on a spec that is part of a galaxy in a universe.......