An aria is a set piece for solo singer that has much more musical elaboration and coherence than recitative. The vocal part is more melodic, and ordinarily the accompaniment includes the orchestra, not just the continuo, as in secco recitative. Here the singer-actor is mulling over his or her emotions at some leisure, “getting his feelings out,” instead of reacting moment by moment, as in recitative. Consequently in arias the repetition of poetic phrases or words is common and, in principle, appropriate.

The standard form for the Baroque Italian opera aria is da capo form, A B A (less usual is free da capo form, A B A′). Both the words and music of A are repeated after B; da capo (“from the head”) is a direction on scores meaning repeat from the beginning. The composer wrote the music for A and B only, leaving the performers to do the rest. Indeed, the singer would do more than just repeat A. He or she would also ornament the music with improvised runs, cadenzas, and so on, so as to create an exciting enhanced effect the second time around.

For connoisseurs of the day, a great deal depended on the A repeats, since it was there that the star singers really dazzled their audiences. Many modern singers have relearned the lost improvisational art of the Baroque era, and we can recapture some of the original excitement on recordings.