Short Summary
Don Alfonso explains to Guglielmo and Ferrando that it is quite possible that their fiancés Dorabella and Fiordiligi could be unfaithful - as all women are.
A bet is made and Don Alfonso hires Despina, Fiordiligi and Dorabella's employee, to help with the intrigue. In disguise, the men finally succeed in seducing each other's fiancée. After Don Alfonso and Despina have broken up the intrigue, it is left to the four young lovers to deal with the consequences of the story.
Storyline
His Dorabella? Ferrando is outraged. She would never cheat on him! But his Fiordiligi, Guglielmo hastens to interject, certainly not him. The two friends agree: the »old philosopher's« assertion that there are no faithful women is inappropriate here.
Finally, a bet is made: The two women are to be put to a test of fidelity. If they allow themselves to be seduced, Don Alfonso wins a hundred zechins; if they remain faithful, the prize goes to Ferrando and Guglielmo. The starting signal for the famous game of disguise and seduction in the last collaboration between Lorenzo Da Ponte and Wolfgang Amadeus Mozart: the two friends pretend to go to war and return in disguise to offer themselves to the women as lovers. Partly on purpose. To break their resistance, Don Alfonso works with the chambermaid Despina, who not only tries to shake the women's morale, but also slips into various disguises herself to help the cause. The seduction succeeds in parts, even in a new combination of couples, and in the end Fiordiligi and Dorabella are even prepared to marry the two »new suitors«. When the charade is resolved, the »old philosopher« triumphs, and in the final chorus everyone vows to be guided by reason in the ups and downs of life.
Fiordiligi and Dorabella sing the praises of their beloved and look forward to the wedding soon. Don Alfonso confronts the sisters with terrible news: Guglielmo and Ferrando have been ordered to the battlefield and must leave immediately. They are already arriving to say their farewells. While the women are heartbroken, Don Alfonso is secretly pleased at how well the men are carrying out his plan. Ferrando and Guglielmo depart to the sound of military music, leaving the women behind in despair.
While Despina prepares breakfast for Fiordiligi and Dorabella, she swears about her working life. When the sisters tell her about their lovers' departure, threatening suicide, Despina laughs at them. The two would return - and if not, there would be plenty of other men. In any case, now is the time to have fun. All men, she explains to the shocked sisters, are unfaithful. So it was only fair to pay them back in kind.
Don Alfonso hires Despina as an accomplice. He asks her for help in setting Fiordiligi and Dorabella up with two men. For the right price, Despina is prepared to help him. Don Alfonso introduces the gentlemen in question to Despina as his best friends. They are Ferrando and Guglielmo, who have disguised themselves. Dorabella and Fiordiligi are furious at the intrusion of strange men into their home. The men declare themselves madly in love with the two women and beg to be heard. Don Alfonso asks for some kindness for his friends. Dorabella and Fiordiligi angrily reject their advances. Guglielmo and Ferrando are delighted by their fiancée's dismissive attitude and see themselves as the winners of the bet. Don Alfonso urges patience: the agreed period has not yet expired.
Don Alfonso cannot believe that he is dealing with two steadfast women. Despina declares the grieving lovers to be mad: after all, love is for pleasure. She wants to make sure that the intrigue picks up speed.
The disguised Guglielmo and Ferrando declare that they want to end their lives because the cruel women will not listen to them. They pretend to take poison and collapse in front of Dorabella and Fiordiligi. Shaken, the women call for help. Don Alfonso has fetched a doctor. It is Despina in disguise. Using unconventional methods, she "cures" the two men in no time at all. Fiordiligi and Dora- bella are now less reluctant until the men become pushy. Doctor Despina explains this behavior with the after-effects of the poison. But the women have no understanding.
The fact that Guglielmo and Ferrando are not supposed to seduce their own fiancée in the course of the »test of fidelity«, but that of the other, was a decision whose radical nature Mozart and Da Ponte must have been well aware of. The evidence suggests that they only made the decision at a late stage or that they changed the constellation several times during the compositional process: For example, the two seducers in Act 1 always address the women in pairs, and the scene instructions according to which Ferrando addresses himself »à Fiord.« and Guglielmo »à Dor.« are only found in later editions of the music, but not in the printed libretto or in Mozart's manuscript. The original Guglielmo aria »Rivolgete a lui lo sguardo«, replaced by »Non siate ritrosi« shortly before the premiere, shows the obvious change of perspective in a particularly interesting way: Guglielmo turns to Fiordiligi here and advises her to turn his gaze to Ferrando - »lui« - while Dorabella should concern herself with him. Not only did Mozart initially omit the personal pronoun »lui« in his score and then add it in a different ink; he actually entered the aria in his own catalog of works under the title »Rivolgete a me lo sguardo«. Where the two women were to turn was therefore evidently up for discussion for a long time.
