The second act is the masterpiece of the opera, and contains in itself music enough to have made any composer immortal. It opens with a serious aria by the Countess ("Porgi amor”) followed by Cherubino’s well-known romanza ("Voi che sapete,”) one of the sweetest and most effective songs ever written for contralto, and this in turn by Susanna’s coquettish song, “Venite, inginocchiatevi,” as she disguises Cherubino. A spirited trio and duet lead up to the great finale, begun by the Count, ("Esci omai, garzon mal nato"). Upon this finale Mozart seems to have lavished the riches of his musical genius with the most elaborate detail and in bewildering profusion. It begins with a duet between the Count and Countess, then with the entrance of Susanna changes to a trio, and as Figaro and Antonio enter, develops into a quintet. In the close, an independent figure is added by the entrance of Marcellina, Barbarina, and Basilio, and as Antonio exits, this trio is set against the quartet with independent themes and tempi.
The third act opens with a duet ("Crudel, perche finora”) for the Count and Countess, followed by a very dramatic scena for the Count, beginning with the recitative, “Hai gia vinta la causa?” which in turn leads up to a lively and spirited sextet ("Riconosci in questo amplesso"). The two numbers which follow the sextet are recognized universally as two of the sweetest and most melodious ever written,—the exquisite aria, “Dove Sono,” for the Countess, and the “Zephyr Duet,” as it is popularly known ("Canzonetta su l’aria. Che soave zeffiretto"), which stands unsurpassed for elegance, grace, and melodious beauty. The remaining numbers of prominent interest are a long and very versatile buffo aria for tenor ("In quegli anni"), sung by Basilio, Figaro’s stirring march number ("Ecco la marcia"), and a lovely song for Susanna ("Deh, vieni, non tardar"). The opera is full of life and human interest. Its wonderful cheerfulness and vital sympathy appeal to every listener, and its bright, free, joyous tone from beginning to end is no less fascinating than the exquisite melodies with which Mozart has so richly adorned it. Like “Don Giovanni” and the “Magic Flute,” the best test of the work is, that it is rounding its first century as fresh and bright and popular as ever.