The plot speeds up in this scene, and the cases of mistaken identity and deception become increasingly complicated. First, we see the hilarious results of Maria’s deception, which bears fruit in Malvolio’s alleged madness. Because he thinks that he shares a secret understanding with Olivia, Malvolio expects her to understand the bizarre things he does and says. Olivia, of course, is bewildered by the change in her normally somber steward, and his apparently illogical responses to her questions make her assume, naturally enough, that he must be out of his mind. She interprets his quotations from the letter as simple insanity: “Why, this is very midsummer madness,” she says after listening to a string of them (III.iv.52). But Malvolio, cut off from reality, willfully ignores these signs that all may not be as he thinks. He fits Olivia’s words to his mistaken understanding of the situation. When she refers to him as “fellow,” for instance, he takes the term to mean that she now thinks more highly of him than she has before (III.iv.57). His earlier egotism and self-regard has become pure, self-centered delusion, in which everything that happens can be interpreted as being favorable to him. As he puts it, “[N]othing that can be can come between me and the full prospect of my hopes” (III.iv.74–75). Malvolio makes a simple mistake—he twists facts to suit his beliefs rather than adapting his beliefs to the facts.
At this point, we realize why Maria’s letter was such a work of genius: in ordering Malvolio to be rude to Sir Toby and the servants, she makes certain that Malvolio will refrain from explaining himself to anyone. Thus, Maria has orchestrated matters such that Malvolio’s behavior will be the justification for the others’ treatment of him as if he were possessed. Sir Toby, with mock-bravery, says that if “Legion himself possessed [Malvolio], yet I’ll speak to him” (III.iv.78–79). Later, Sir Toby and the servants decide to treat Malvolio “gently, gently,” a recommended manner of dealing with people thought to be possessed. Once Malvolio leaves, the three plot to “have him in a dark room and bound”—another common treatment for madmen (III.iv.121). As Sir Toby notes, Olivia already thinks that Malvolio is mad, so they can torture him until they grow tired of it. It is here that we begin to feel pity for Malvolio. His humiliation may be richly deserved, but there is a kind of overkill in Sir Toby and Maria’s decision to lock him away. He seems to be punished cruelly for what are, after all, minor sins, and our sense that Malvolio is being wronged only increases in Act IV.
Sir Toby’s trickery in frightening Cesario and Sir Andrew with fearsome tales about each other’s prowess sets the stage for yet another wrinkle in the web of deception. Viola, who has been in disguise throughout the play, is now mistaken for yet a third person—her own brother, Sebastian. Antonio’s mistake is made much more poignant by his badly timed arrest and his grief and anger at thinking that Sebastian has stolen his money and betrayed him. He tells Viola, who is disguised as Cesario but who he thinks is Sebastian, that her beautiful features conceal a wickedness of soul: “In nature there’s no blemish but the mind. / None can be called deformed but the unkind” (III.iv.331–332). His anguish here is touching—far more touching than the flowery grief of Olivia, say, or the lovesick posturings of Orsino. It moves us because we know that for Antonio there can be no happy endings. A comedy like Twelfth Night ends, inevitably, with marriages—but there is no one for Antonio to marry, since he loves only Sebastian.
Meanwhile, Antonio’s mistaken insistence that Sebastian knows him and owes him money causes his arresting officers to think that Antonio, in turn, is insane. The disguises, secret identities, and crossed lines of communication lead to humorous circumstances, but they also tinge the action with hints of insanity and tragedy. Antonio is arrested, and Malvolio is confined as a madman—and the audience begins to feel that things are going too far. In the world of Twelfth Night, disorder and the gentle madness of romantic infatuation are celebrated, but there is a limit to how much anarchy can dominate the stage before comedy gives way to tragedy. As in a tragedy, everything in Twelfth Night falls into disorder as the play moves toward the conclusion; because the play is a comedy, however, we know that matters will be put right in the end.