Wolfgang Mozart was, if you believe the movie “Amadeus,” a bit of a rebel, like today’s pop stars, but with real talent. And when you’re always petitioning for support from a patron, there’s much to rebel against. When Mozart wrote the music for “La Clemenza di Tito,” he was reined in by the   requirements of his employer. While he might have bent the rules of opera, he was not able to run wild and the musical restraints makes this piece good, but not great. This piece has other curiosities.

As the name indicates, this is an an Italian opera, even though the composer is Austrian-born.  The libretto is in Italian by Caterino Mazzola. Domenico Guardasoni commissioned the piece for the House of Bohemia to honor the up-coming coronation of Leopold II, King of Bohemia. “La Clemenza” was first performed on 6 September 1791 in Prague.

Mozart would die a few months later (5 December 1791).

The opera was popular after Mozart’s death, but there are things that are no longer popular: castrating male singers. The role of Sesto was written for a soprano castrato or mezzo-soprano. There is only one role for a male opera singer who has not been physically altered–the role of Tito, the Roman Emperor which is sung by a tenor. The Metropolitan Opera’s production is filled with sumptuous costumes and gorgeous voices. The opera might be a lesser work of Mozart, but it still has the touch of genius and the Met’s production gives the opera a full measure of respect. The Met, of course, couldn’t get a soprano castrato to play Sesto, but instead goes the way of Japan’s Takarazuka, having women play the roles of Annio and Sesto.

The year is 79 and Tito (Giuseppe Filianoti) has already usurped the throne from Vitellio. But Vitellio had a daughter who, to remind you of her role, is named Vitellia  (Barbara Frittoli). She plots revenge, but this is also a love story. Annio (Kate Lindsey) is in love with Servilia (Lucy Crowe), the sister of Sesto. Sesto (Elina Garanca), male friend of Tito, is in love with Vitellia. Tito  wants to marry Servilia but doesn’ t know that Annio, his male friend, and Servilia are in love.

Vitellia convinces Sesto to murder his best friend, the emperor, but don’t worry. By the title, you know this is all about clemency (la clemenza) and a good and fair ruler so you can guess there will be a happy ending.

“La Clemenza di Tito” will be on PBS Great Performances at the Met on Sunday, 14 April 2013 at noon on PBS. Check local listings.