Bosola hears a shriek “from the Duchess’ lodging.” In his position as intelligencer, he feels obligated to investigate. He encounters Antonio armed with a sword, and in their questioning of what each other is doing out, Antonio says he was setting the duchess’s jewels, and Bosola says he was saying his prayers. They exchange bitter words, and after Antonio leaves, Bosola sees a note dropped by Antonio indicating that the duchess has been “deliver’d of a son, ’tween the hours twelve and one” of the night. He wonders who the father is and resolves to send a letter to her brothers, who are in Rome, to notify them of his discovery.

Scene 4 begins with the cardinal and Julia in Rome. They converse about their relationship but are interrupted by a servant bringing the news that Castruchio has arrived in Rome. Delio, one of Julia’s “old suitors,” says Castruchio is very tired from his riding, but their conversation as well is interrupted by the servant, who says Ferdinand, having seen Bosola’s letter, is “out of his wits.” Before exiting, Delio expresses his fear that Antonio has been betrayed.

He has, and the brothers respond to the letter containing that betrayal. In his rage, Ferdinand calls for them to take violent measures against the duchess and vows to murder her. The cardinal, surprised by his brother’s extreme anger, asks him to calm down. But at the end of the scene and act, Ferdinand further vents his rage before vowing to act only after discovering who impregnated the duchess.

Analysis

The rancor between Antonio and Bosola derives from both the tension each feels over the duchess’s pregnancy and birth and their headstrong, determined, and unguarded natures. Their mutual accusations show, however, that in Ferdinand’s court, evil is expected, and situations arising in it tend to reveal the worst of human nature. Antonio, like the duchess, is in agreement with Bosola’s affirmation that people are essentially the same: “the great are like the base; nay, they are the same, when they seek shameful ways to avoid shame.” It’s no surprise that Bosola deems Antonio a “false friend” or that he learns of the duchess’s childbearing not directly but through Antonio’s dropping of the paper noting their son’s birth. Again, indirectness, duplicity, and rumor prevail; Bosola, not having seen the duchess give birth, must rely on a piece of paper to confirm that fact. In that note, great emphasis is placed on astrology, but its prediction of short life and a violent death for this eldest son is wrong.

Julia lies to her husband, Castruchio, an act that contrasts with her professed constancy to the cardinal. The cardinal’s advice for her to avoid “a voluntary torture, which proceeds out of your own guilt” over betraying her husband introduces the cardinal’s emphasis on conscience. He is, though, not feeling any shame in making Castruchio a cuckold. Prudence nonetheless prompts the cardinal to retreat when he suspects Castruchio is about to enter. Julia reprises the cardinal’s refrain of “still you are to thank me” when she asks Delio what the condition for his present of money is; like the cardinal, Julia assumes affection is tied to bargaining and making demands, and that love is not given freely. Julia, despite her wanton nature, does recognize that gold does not match the qualities of nature; she has not entirely abandoned the natural world. Whatever Delio’s intentions were upon coming to Rome, he spends this scene flirting with Julia and fails to protect Antonio from the release of the news of the duchess’s childbirth. Delio has not even managed to judge if Julia’s “wit, or honesty” was on display when she promised to ask Castruchio if she could be Delio’s mistress.

Ferdinand’s rage in response to the news of the duchess’s newborn child contrasts with the cardinal’s counsel for reason and restraint. Ferdinand ironically criticizes the duchess for secretly having “most cunning bawds to serve her turn,” not realizing that he has employed Bosola for similarly underhanded purposes. His distrust of not just the duchess, but women in general, is revealed by his criticism of men who “trust their honour” to the “weak bulrush” of woman. Ferdinand suspects the duchess has not only given birth illegitimately, but that she has also mated with a man far below her station. The cardinal, echoing Bosola’s soliloquy on man’s deformed nature, says nothing “makes man so deform’d, so beastly as doth intemperate anger.” Ferdinand continues the theme of distortion by vowing that he “will only study to seem the thing I am not,” but Ferdinand’s hidden guilt comes through in his comment that “it is some sin in us, Heaven doth revenge by her.” The duchess, rather than being valued in herself, is merely a vessel by which heaven sends its moral judgment upon the brothers.