L'amerò, sarò costante (Il re pastore)

Il re pastore was written for the visit of Archduke Maximilian Franz to Salzburg and performed there on 23 April 1775, when Mozart was nineteen. Metastasio's libretto, already set by a dozen composers, concerns a shepherd who proves to be the rightful king of Sidon and is asked to give up the woman he loves for reasons of state. Mozart compressed it into two acts and treated it as a serenata rather than a staged opera. L'amerò, sarò costante, with its obbligato solo violin, is the number that keeps the work in circulation, sung far more often than the piece is given complete.