The curtain is withdrawn, and we discover the lovers preparing for their wedding.  Figaro is taking the dimensions of a room, and the first motive of a duet illustrates his measured paces; Susanna is trimming a hat, and her happiness and her complacent satisfaction with her handiwork are published in the second motive, whose innocent joy explodes in scintillant semi-quavers in the fiddles at the third measure.  His labors ended, Figaro joins Susanna in her utterances of joy.  But there is a fly in the ointment, Why has Figaro been so busily measuring the room?  To test its fitness as their chamber, for the Count has assigned it to them, though it is one of the best rooms in the palace.  He points out its convenient location (duet:  “Se a caso madama"); so near the room of the Countess that her maid can easily answer the “din din” of her bell, and near enough to the room of the Count that his “don don” would never sound in vain should he wish to send his valet on an errand.  Altogether too convenient, explains Susanna; some fine day the Count’s “don don” might mean a three-mile journey for the valet, and then the devil would fetch the dear Count to her side in three paces.  Has he not been making love violently to her for a space, sending Don Basilio to give her singing lessons and to urge her to accept his suit?  Did Figaro imagine it was because of his own pretty face that the Count had promised her so handsome a dowry?  Figaro had pressed such a flattering unction to his soul, but now recalls, with not a little jealous perturbation, that the Count had planned to take him with him to London, where he was to go on a mission of state:  “He as ambassador, Figaro as a courier, and Susanna as ambassadress in secret.  Is that your game, my lord?  Then I’ll set the pace for your dancing with my guitar” (Cavatina:  “Se vuol ballare").

Almaviva’s obedient valet disappears, and presto! in his place we see our old friend, the cunning, resourceful barber and town factotum of the earlier days, who shall hatch out a plot to confound his master and shield his love from persecution.  First of all he must hasten the wedding.  He sets about this at once, but all unconscious of the fact that Dr. Bartolo has never forgiven nor forgotten the part he played in robbing him of his ward Rosina.  He comes now to let us know that he is seeking revenge against Figaro and at the same time, as he hopes, rid himself of his old housekeeper, Marcellina, to whom he is bound by an obligation that is becoming irksome.  The old duenna has been casting amatory glances in Figaro’s direction, and has a hold on him in the shape of a written obligation to marry her in default of repayment of a sum of money borrowed in a time of need.  She enlists Bartolo as adviser, and he agrees to lay the matter before the Count.  Somewhat early, but naturally enough in the case of the conceited dotard, he gloats over his vengeance, which seems as good as accomplished, and celebrates his triumph in an air ("La vendetta!").  As she