In becoming suspicious of the Duchess, Ferdinand hires Bosola to spy on her, while the Duchess thinks she has employed him as head of her stables. The Duchess unfortunately comes to have trust in Bosolo, and he discovers that she has married Antonio and had children with him in secret. As Ferdinand’s spy, he reveals the information to the Duke, and is then ordered by Ferdinand to kill the Duchess. After the Duchess’s secrets are revealed, the play unveils into great tragedy as the brothers seek out revenge that results in the death of the Duchess, Antonio, and their children; the Duchess’s hand-maid, Cariola, Bosola, the Cardinal, the Cardinal’s mistress and servant, and even Ferdinand. One of the motives often used in several other Jacobean plays is that of incest.
It can be thought that incestual feelings for his twin sister, the Duchess, are the real reason that Ferdinand is so dead set on keeping his sister from remarrying. This is not obvious in the play, but implied, as there exists evidence of these feelings throughout the play. For example, he makes many sexual innuendos aimed at his sister throughout the entire play, such as we see here: Ferdinand: And women like the part, which, like the lamprey,Hath ne’er a bone in’t. Duchess: Fie, sir!Ferdinand: Nay,I mean the tongue Act 1, Scene iiAlso in Act 1, Ferdinand refers to his sister offensively as a “lusty widow.
” Another piece of evidence which hints at Ferdinand’s possible incestuous feelings for his sister are in his last words, where he possibly shows recognition to these feelings, when he says,”My Sister, O my sister! There’s the cause on’t/ Whether we fall by ambition, blood, or lust, / Like Diamonds, we are cut with out own dust,” (Act 5, Scene 5) linking back to the first Act in which the Duchess says, “Diamonds are of most value / They say, that have passed through most jewellers’ hands,” (Act 1, Scene 2)where the Duchess compares herself to a diamond, Ferdinand is cut by her dust. This shows that it is possible he realizes his destruction by the dust that he and his sister share. Even though he may have admitted to his downfall, it is unlikely that he truly understood his feelings partly because of his sickly state of mind at the time of his death.