I’ m in Dresden, Berlin, and Amsterdam for an art-writing trip and, while in Dresden, to experience Wagner’s Ring cycle. Since Prague is only a two-hour train trip from Dresden, we went for a day.

The roughly 30-piece collection once belonged in Masaryk’s London apartment and was donated by the family of his wartime secretary, Lumír Soukup. Among other things, it includes a painting by Oskar ...