40 years without Escher (27 March 1972)
"I try in my prints to testify that we live in a beautiful and orderly world, not in a chaos without norms, even though that is how it sometimes appears. My subjects are also often playful: I cannot refrain from demonstrating the nonsensicalness of some of what we take to be irrefutable certainties. It is, for example, a pleasure to deliberately mix together objects of two and three dimensions, surface and spatial relationships, and to make fun of gravity."
Escher on Escher: exploring the infinite (1989), edited by J. W. Vermeulen and H. N. Abrams