— M. C. Escher Dutch graphic artist 1898 - 1972
Variant translations: Are you really sure that a floor can't also be a ceiling?
I can't keep from fooling around with our irrefutable certainties. It is, for example, a pleasure knowingly to mix up two and three dimensionalities, flat and spatial, and to make fun of gravity.
1950's, On Being a Graphic Artist', 1953
Context: In my prints I try to show that we live in a beautiful and orderly world and not in a chaos without norms, as we sometimes seem to. My subjects are also often playful. I cannot help mocking all our unwavering certainties. It is, for example, great fun deliberately to confuse two and three dimensions, the plane and space, or to poke fun at gravity. Are you sure that a floor cannot also be a ceiling? Are you absolutely certain that you go up when you walk up a staircase? Can you be definite that it is impossible to eat your cake and have it?