"Perceptual reality is entirely generated by our brain. We hear voices and meaning from air pressure waves. We see colors and objects, yet our brain only receives signals about reflected photons. The objects we perceive are a construct of the brain, which is why optical illusions can fool the brain."
For centuries artists have been pushing our perceptual limits and if you ever get lucky enough, from the right angle, you may just catch a glimpse into the practical artistic applications of optical illusions and the way our mind interprets them.