For the first time in the history of music, words and music were united in the service of meaning and emotion. This didn’t occur in any other case, and this work was only magnified by the science and the genius of the composer. It's all about subtlety and finesse: Monteverdi succeeds in synthesizing the madrigalesque knowledge of a bygone era and lays the foundations of the "seconda pratica": from that point on, compositions aim to musically translate the emotions of men and paint their fragility through soloist vocalists carried by a group of accompanying instruments, the continuo. These instrumentalists must develop colors of orchestration and personal improvisation in the service of an emotion. They are the link, or rather the musical translation, between notes lying on a staff and a poetic text.
La Musica, an allegorical character, sings in the prologue of the power of Orpheus whose music is so beautiful that it manages to move the gods, charm men and animals and move trees and rocks alike. Orpheus and Eurydice marry. Through a messenger, Orpheus learns that Eurydice is dead, bitten by a snake; he decides to go to the Underworld to save her: Hope accompanies Orpheus to the gates.
Meeting Charon, he tries to subdue him with his singing. Without success, he tries again but with his lyre. Charon falls asleep and Orpheus takes the opportunity to enter the Underworld.
Touched by the music of Orpheus, Proserpina, Queen of the Underworld, wife of Pluto, convinces him to let Eurydice go. Pluto agrees on one condition: Orpheus must not look back while Eurydice follows him on his way back to the light and to life.
He leaves, with Eurydice following him, but he can't help but turn around: his wife disappears. Overwhelmed with grief, Orpheus is taken to heaven by his father Apollo and becomes immortal, equal to the gods: he will be able to see Eurydice in the stars.