Optical illusions such as the Penrose triangle ... demonstrate that you do "create" an imagined reality out of the raw material of vision, what Mr. Humphrey calls a "magical mystery show that you lay on for yourself," yourself being the rest of the brain.
But I don't think of myself as the rest of my brain, and I doubt if anyone else does, either. The principal problem in all of this is that it has less to do with explaining a given phenomenon than with explaining a given phenomenon in a particular way, in this case in terms of evolutionary theory. So we start with the theory and then show how the phenomenon can be understood in terms of said theory. But the fact that one can do that only demonstrates one's ingenuity, since, absent hard evidence, it remains purely speculative.