About the work
Demofoonte is an opera seria in three acts by Josef Mysliveček, setting Pietro Metastasio's libretto that had premiered at the Viennese court in 1733 and draws on an ancient legend transmitted by Hyginus. Mysliveček's setting premiered at the Teatro San Carlo in Naples on 20 January 1775, marking the nameday of King Charles III of Spain.
Plot
The Thracian king Demofoonte must sacrifice a virgin to Apollo every year. His son Timante is secretly married to Dircea, who has been chosen for the sacrifice. Only through letters that come to light is it revealed that Dircea is in fact the king's own daughter, and Timante not his biological son — making the marriage lawful, fulfilling the oracle and ending the sacrifice.
Cultural significance
The premiere was a success; the prima donna Antonia Bernasconi took arias from the opera with her to her next engagement in London.