Wow neat, I hadn't seen this before. Besides watching the animations, the most interesting thing was the AMS article by Lenstra and de Smit: https://www.ams.o

Wow neat, I hadn't seen this before. Besides watching the animations, the most interesting thing was the AMS article by Lenstra and de Smit: https://www.ams.org/notices/200304/fea-escher.pdf https://www.ams.org/notices/200304/fea-escher.pdf It explains all the math, shows Escher's work drawings, etc. Escher himself didn't seem to be completely cognizant of the math, so he worked by intuition and eyeballed things, but he came to a very close approximation of what the mathematicians worked out decades later.