I don't believe in a soul or spirit. I believe that we are the universe observing itself from different perspectives. Within our consciousness is the universe and everything in it (although we don't actually use enough of our brain power to ever tap the expansive amount of information contained within ourselves). What we see of that with our senses is reality. Reality isn't one certain thing, either. Every person has their own reality, and each is as true as any other.

As for when you trip, I think it's like looking within your own consciousness (and, therefore, seeing or feeling more of the universe than our normal senses can).