The Rabbit Duck
Do you notice the rabbit first, or the duck? This image originally appeared in a German humor magazine in 1892, reportedly inspiring some profound philosophical thoughts from Ludwig Wittgenstein.
The Hering Illusion is an optical illusion discovered by German physiologist Ewald Hering in 1861. Both vertical lines are straight, despite the appearance that they are bowed outward. The distortion is created by the pattern of lines in the background, simulating a false perspective of depth.