i took this weird class in h.s. about all kinds of fringe-math topics. Escher was a big topic for a while. teacher showed us vids and explained some of the geometry and general math-yness behind some of his work. then we had a project to do an escher-style picture (one of the ones with redundant animals/objects morphing into other animals/things). its wicked hard, even when u like really understand the idea behind it and all.