Afterward she is joined by her father. Then Leonore (as Fidelio) enters the courtyard. She has a basket of provisions and also is carrying some fetters which she has taken to be repaired. Marcellina, seeing how weary Leonore is, hastens to relieve the supposed youth of his burden. Rocco hints not only tolerantly but even encouragingly at what he believes to be the fancy Fidelio and Marcellina have taken to each other. This leads up to the quartet in canon form, one of the notable vocal numbers of the opera, "Mir ist so wunderbar" (How wondrous the emotion). Being a canon, the theme enunciated by each of the four characters is the same, but if the difference in the sentiments of each character is indicated by subtle nuance of expression on the part of the singers, and the intonation be correct, the beauty of this quartet becomes plain even at a first hearing. The participants are Leonore, Marcellina, Rocco, and Jacquino, who appears toward the close. "After this canon," say the stage directions, so clearly is the form of the quartet recognized, "Jacquino goes back to his lodge."
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Rocco then voices a song in praise of money and the need of it for young people about to marry. ("Wenn sich Nichts mit Nichts verbindet"—When you nothing add to nothing.) The situation is awkward for Leonore, but the rescue of her husband demands that she continue to masquerade as a man. Moreover there is an excuse in the palpable fact that before she entered Rocco's service, Jacquino was in high favour with Marcellina and probably will have no difficulty in re-establishing himself therein, when the comely youth Fidelio, turns out to be Leonore, the faithful wife of Florestan.
Through a description which Rocco gives of the prisoners, Leonore now learns what she had not been sure of before. Her husband is confined in this fortress and in its deepest dungeon.
A short march, with a pronounced and characteristic rhythm, announces the approach of Pizarro. He looks over his despatches. One of them warns him that Fernando, the Minister of State, is about to inspect the fortress, accusations having been made to him that Pizarro has used his power as governor to wreak vengeance upon his private enemies. A man of quick decision, Pizarro determines to do away with Florestan at once. His aria, "Ha! welch' ein Augenblick!" (Ah! the great moment!) is one of the most difficult solos in the dramatic repertoire for bass voice. When really mastered, however, it also is one of the most effective.
Pizarro posts a trumpeter on the ramparts with a sentry to watch the road from Seville. As soon as a state equipage with outriders is sighted, the trumpeter is to blow a signal. Having thus made sure of being warned of the approach of the Minister, he tosses a well-filled purse to Rocco, and bids him "for the safety of the State," to make away with the most dangerous of the prisoners—meaning Florestan. Rocco declines to commit murder, but when Pizarro takes it upon himself to do the deed, Rocco consents to dig a grave in an old cistern in the vaults, so that all traces of the crime will be hidden from the expected visitor.
Leonore, who has overheard the plot, now gives vent to her feelings in the highly dramatic recitative: "Abscheulicher! wo eilst du hin!" ("Accursed one! Where hasten'st thou!"); followed by the beautiful air, "Komm Hoffnung" (Come, hope!), a deeply moving expression of confidence that her love and faith will enable her, with the aid of Providence, to save her husband's life. Soon afterwards she learns that, as Rocco's assistant, she is to help him in digging the grave. She will be near her husband and either able to aid him or at least die with him.
The prisoners from the upper tiers are now, on Leonore's intercession, permitted a brief opportunity to breathe the open air. The cells are unlocked and they are allowed to stroll in the garden of the fortress, until Pizarro, hearing of this, angrily puts an end to it. The chorus of the prisoners, subdued like the half-suppressed joy of fearsome beings, is one of the significant passages of the score.