This is a well known fact that M. C. Escher - the Dutch artist whose graphic work achieved recognition towards the end of the 20th century, especially among mathematicians - consistently denied his ability to understand or do mathematics. His son George has observed that
Father had difficulty comprehending that the working of his mind was akin to that of a mathematician. He greatly enjoyed the interest in his work by mathematicians and scientists, who readily understood him as he spoke, in his pictures, a common language. Unfortunately, the specialized language of mathematics hid from him the fact that mathematicians were struggling with the same concepts that he was.
Doris Schattschneider seem to pinpoint the source of the conflict:
In Escher's mind, mathematics was what he encountered in school work - symbols, formulas, and textbook problems to solve using prescribed techniques. It din't occur to him that formulating his own questions and trying to answer them in his own way was doing mathematics.
Escher (born 1898) went to school during the first two decades of the 20th century. How much of Escher's understanding of what mathematics is is shared by the modern day students?