Do you perceive the world or only your own mental images?
Argument presented in prose
Look around you. What do you see? Perhaps you'll say, “Well, I see the world, of course! The desk; the computer; my partner. What could be clearer?” However, consider that when you look at a straight stick half submerged in water, an optical illusion leads you to see something bent. Now remember, the actual physical stick is straight. The only bent thing for you to see is something mental—a mental image of the stick. And as there isn't any difference in the kind of thing you see in the case of an optical illusion and in normal perception, this demonstrates that in normal visual perception, instead of seeing physical objects, you actually only see your own mental images!