Music: Old Pros, New Works

German-born Composer Paul Hindemith, 61, and French-born Composer Darius Milhaud, 65, both of whom have lived and taught in the U.S. for long stretches, are furiously prolific writers of serious music. Between them, so far, they have published more than 500 works. Last week, on opposite sides of the Atlantic, the two tireless pros conducted their latest compositions.

Musical Chronicle. Hindemith's was the more ambitious work—a five-act opera entitled The Harmony of the World, premiered in Munich at the city's Opera Festival. It was his first opera since Mathis der Maler (1938). The...