From the Introduction:
You don't belong here.
Something about you is foreign to this universe and it wants you to leave.
There is a constant pressure on you that pushes you against the Brane, the barrier between universes.
Because of this you can sense the Brane, and the presence of other people and things who are also being forced out of this reality, or trying to make their way in.
Only the fact that you are a thinking being keeps you from being pushed into the flux, the unreal place between universes in which all things are broken down. You can however allow yourself to be pushed part way which allows to use the Brane to travel within a universe, to pull things from the outside in, or push them out.
There are those who guard this world from invaders from beyond, they have discovered you and given you a choice, join them, or be sent away.
You are one of the ones who chose to stay.