I have been fascinated with the concept of perception for a very long time. I recently read several books on quantum physics (very low level explanations) and realize how much of what we understand depends on perception. The act of observation changes the observed.
There is more to it than that. What we see is based on what we already know. The brain, a supreme pattern-matching machine, identifies any new visual input with existing patterns it already recognizes. When you see something truly new, it’s difficult to comprehend it as something unique. It simply gets associated with something you already understand and filed away accordingly.
Perception is a form of projection. We see what we expect to see. Nothing more.