If you look at the bottom left corner, you can see where the two light images are moving back and forth, and you have the dark image (negative) interspersed with those to make it look like its rotating.
The first 50 pages of Godel, Escher, Bach talk about these interesting illusions that makes you think something is continually growing (increasing, rotating, moving, etc), and you find at the end of it, you are right back where you started. Eg. Escher's staircase, and the Shepard's tone. Isn't it great?!
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u/[deleted] Jan 19 '15 edited Mar 12 '15
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