Each summer, philosopher-king Leon Botstein summons New Yorkers to his plaisance on the Hudson for Summerscape, arguably the world’s most intellectually rigorous arts festival. The Spiegeltent—a Belle Époque folly in stained glass, mirrors, and mahogany—is the motley fool in the mix, spangling Leon’s concerts and seminars with cabaret, drag shows, and jazz. This year as last, the Hot Sardines will pack the floor with dancers of every tint, vintage, and gender in a joyful democracy of swing. —E.E.