[math-fun] Draft of my July 2019 essay

This month I plan to publish a Mathematical Enchantments essay on the 14th, rather than the 17th, so that I can link to it in my third pitch for Christian's Big Internet Math-Off on the 15th. But as always comments are welcome at any time since it's easy to make edits in WordPress. The podcast episode I refer to can be heard at https://kpknudson.com/my-favorite-theorem/2019/7/10/episode-44-james-propp but the essay is designed to stand on its own. Thanks, Jim Propp