Book excerpt: What makes these puzzles so special? Not only does each one illustrate some of the most classic theories in math, logic, and perception, but they're eye-catching too. Stare at brilliantly hued concentric circles, inspired by the "video active" paintings of the Parisian artist Isia Leviant; if you continue to look long enough, a spinning white blur will appear. Or imagine that you have a drawerful of socks in different colors--7 red, 7 yellow, and 7 green pairs. If you pulled some out in complete darkness, how many would you have to take before you'd be sure of having a pair in each color? Or solve word puzzles, paradoxes, and the mystery of the rolling photo cube.