The ideas that are basic to [my work] often bear witness to my amazement and wonder at the laws of nature which operate in the world around us. He who wonders discovers that this is in itself a wonder. By keenly confronting the enigmas that surround us, and by considering and analyzing the observations that I had made, I ended up in the domain of mathematics.
Source, in full
Quote of Escher 1959 - in the introduction of M.C. Escher: The Graphic Work (1978) p. 8 - translated from the original book in Dutch: M.C. Escher - Grafiek en Tekeningen, publisher, Koninklijke Erven J.J. Tijl N.V. Zwolle, 1959