When Leonard Bernstein’s “Mass” opened the Kennedy Center in 1971, it was the social event of the season. And tensions were high. America was polarized by the anti-war movement; by the Pentagon Papers, which had been released earlier that summer; by riots sparked by racial injustice; and by divisive political discourse. At that star-studded premiere, the piece, which was commissioned by Jacqueline Kennedy Onassis, was criticized for its treatment of Catholic liturgy and its overtly political intentions — including the phrase “Give us peace.” President Richard Nixon refused to attend (He had the FBI surveil the Jewish composer for years...