I never really thought of Escher as an artist I always associated him mathematics, his work was on the wall in the maths department in school and university but not seen in the art departments. His calculated work is vivid and has impossible realism a direct contrast to the work of post- modernists who were his contemporaries. Describing his method he said that the element of mystery was to be found veiled in the ordinary. Escher was ordinary and has remained a mystery.
The artist who created some of the most memorable images of the 20th century was never fully embraced by the art world.
http://www.theguardian.com/artanddesign/2015/jun/20/the-impossible-world-of-mc-escher