The history of Lucrezia Borgia, daughter of Rodrigo Borgia, afterwards
Pope Alexander VI., and sister of Caesar Borgia, is too well known to
need recapitulation. It is necessary to the comprehension of the story
of the opera, however, to state that she had an illegitimate son,
named Genarro, who was left when an infant with a fisherman, but who
subsequently entered the Venetian army and rose to an eminent rank.
The opera opens with a brilliant festival in the gardens of the
Barberigo Palace, which is attended by Genarro, Orsini, and others,
all of them cordial haters of the detestable Borgias. While they are
telling tales of Lucrezia's cruel deeds, Genarro lies down and goes to
sleep, and Orsini in a spirited aria ("Nelle fatal di Rimini") relates
to his companions the story of Genarro's gallantry at the battle of
Rimini. As they leave, Lucrezia approaches, masked, in a gondola, and
is received by Gubetta, with whom she has come to Venice on some
secret errand. She discovers Genarro asleep, and expresses her delight
at his beauty, and at the same time her maternal love, in a brilliant
aria ("Com'e bello"). As she kisses his hand he wakes, and in the duet
which follows tells her the story of his early life in an exquisite
romanza ("Di pescatore ignobile"), which is one of the most familiar
numbers in Italian opera. He begs her to reveal her name, but she
refuses. As he continues to implore her, his friends return and
denounce her to Genarro as the hated Borgia, in a concerted number
("Chi siam noi sol chiarirla") of great dramatic power, which closes
the first act.

The second act opens in the public square of Ferrara, with the palace
of the Borgias on the right. The Duke Alphonso, Lucrezia's husband,
who has been observant of Lucrezia's attachment to Genarro, vows
vengeance in a passionate aria ("Vieni la mia vendetta"). In the next
scene Genarro, who has been taunted by his friends with being a victim
of Lucrezia's fascinations, recklessly rushes up to the palace door
and strikes off the first letter of her name with his dagger. When
Lucrezia discovers the insult, she demands of the Duke that the guilty
person shall be arrested and condemned to death. The Duke has already
seized Genarro, and agrees to carry out his wife's demands. When the
prisoner is brought before them for judgment, she is horror-stricken
to find he is her son. She implores his life, but the infuriated Duke
retaliates upon her with the declaration th