This article: In his garden, Seneca learns from the god Mercurio that he is soon to die. The order duly arrives from Nerone, and Seneca instructs his friends to prepare a suicide bath. His followers try to persuade him to remain alive, but he rejects their pleading. "The warm current of my guiltless blood shall carpet with royal purple my road to death." At the palace Ottavia's page flirts with a lady-in-waiting, while Nerone and the poet Lucano celebrate the death of Seneca in a drunken, cavorting song contest, and compose love songs in honour of Poppea. Elsewhere in the palace, Ottone, in a long soliloquy, ponders how he could have thought to kill Poppea with whom he remains hopelessly in love. He is interrupted by a summons from Ottavia, who to his dismay orders him to kill Poppea. Threatening to denounce him to Nerone unless he complies, she suggests that he disguise himself as a woman to commit the deed. Ottone agrees to do as she bids, privately calling on the gods to relieve him of his life. He then persuades Drusilla to lend him her clothes.
In the garden of Poppea's villa, Arnalta sings her mistress to sleep while the god of Love looks on. Ottone, now disguised as Drusilla, enters the garden and raises his sword to kill Poppea. Before he can do so, Love strikes the sword from his hand, and he runs away. His fleeing figure is seen by Arnalta and the now awakened Poppea, who believe that he is Drusilla. They call on their servants to give chase, while Love sings triumphantly "I protected her!" contains an answer for the question: Who protects the target of the man that is hopelessly in love?, what is it ?


Love