About the work
Demetrio is an opera seria by Christoph Willibald Gluck on Pietro Metastasio's libretto of the same name. It premiered on 2 May 1742 at the Teatro San Samuele in Venice; a later 1749 performance at the Ospedale dei Mendicanti, also in Venice, ran under the title Cleonice.
Plot
The prince Demetrio, believed dead, has grown up under the name Alceste with his guardian Fenicio. After the usurper Alessandro's fall, Queen Cleonice rules and loves Alceste without knowing his true identity; political pressure keeps them apart at first. A letter finally reveals Alceste's origin, allowing him to reclaim his throne and marry Cleonice.
Cultural significance
Only eight arias survive from Gluck's score, with the music considered partly lost. Metastasio's text, set by more than fifty composers including Caldara, Hasse and Vivaldi, ranks among his most successful librettos.