Origins of opera
"Dafne" by Jacopo Peri was the earliest composition considered opera, as understood today, although with only five instrumental parts it was much more like a chamber opera than either the preceding intermedi or the operas of Claudio Monteverdi a few years later. It was written around 1597, largely under the inspiration of an elite circle of literate Florentine humanists who gathered as the "Camerata". Significantly, "Dafne" was an attempt to revive the classical Greek drama, part of the wider revival of antiquity characteristic of the Renaissance. The members of the Camerata considered that the "chorus" parts of Greek dramas were originally sung, and possibly even the entire text of all roles; opera was thus conceived as a way of "restoring" this situation. The libretto was by Ottavio Rinuccini, who had written some of the 1587 Medici intermedi, in which Peri had also been involved; Rinuccini appears to have recycled some of the material, at least from the scene illustrated at right. Most of the music for "Dafne" is lost (the libretto was printed and survives), but one of Peri's many later operas, "Euridice", dating from 1600, is the first opera score to have survived to the present day.
Demetrio (1773)
The opera was first performed at the Teatro Nuovo in Pavia on 24 May 1773. It was commissioned to serve as the first opera to be played in a newly constructed theater in the city, and it was considered to be a great honor for Mysliveček to compose the inaugural opera. The organizers were able to attract only one distinguished singer for the cast, however: the soprano Lucrezia Aguiari, whose name has been linked romantically to Mysliveček's erroneously in earlier musicological literature. Her aria "Agitata in tanti affanni" was widely disseminated in late eighteenth-century aria collections.
Act I, scene 1 - Aria of Olinto, "Di quell'ingiusto sdegno" 
Act I, scene 2 - Aria of Cleonice, "Fra tanti pensieri" 
Act I, scene 3 - Aria of Barsene, "Non ti lagnar del fato" 
Act I, scene 4 - Aria of Fenicio, "Ogni procella infida" 
Act I, scene 5 - Aria of Cleonice, "Se non posso su quel trono" [a non-Metastasian text] 
Act I, scene 6 - Aria of Fenicio, "Il ciel rispetta il soglio" 
Act I, scene 7 - Aria of Alceste, "Scherza il nocchier talora" 
Act I, scene 9 - Duet for Cleonice and Alceste, "D'un amoroso accento" [a non-Metastasian text]