[karmakaze]

Even the human vision system is hallucinating all the time. The difference is that when we're awake we have another filter that separates the unreal hallucinations from the ones that are much more likely to match reality.

I experienced this very memorably coming back from vacation where there were little lizards seen while walking to and from the beach. When I got back home to my cold climate, I 100% saw a lizard skit across the sidewalk--it was a leaf.