It seems that the surgeon is drunk and cannot come, and although Olivia tries to find out who is responsible for this bloody business, she cannot, for confusion reigns as Sir Toby and Sir Andrew help one another off to bed.
The key to the solution of all of this confusion now enters: it is Sebastian. He apologizes to Olivia for having injured Sir Toby. Orsino is the first to express astonishment at the identical appearance of Sebastian and Cesario. It is almost impossible to distinguish between them, except by the colors of their clothes. Sebastian then reminds Olivia of the words which they exchanged only a short time ago, and he calls her his "sweet one." He joyfully recognizes Antonio and confesses how "the hours [have] racked and tortured" him since he lost him. Like Orsino, Antonio is amazed. He compares Cesario and Sebastian to "an apple, cleft in two." Viola (Cesario) begins to speak then; she tells Sebastian that he is very much like a twin brother who she fears perished in a "watery tomb." Her father was Sebastian; he had a mole on one brow — and at this point, Sebastian interrupts her: so did his father. Moreover, both agree that this man died when they were thirteen years old.
Viola then reveals that her real identity is hidden by "masculine usurp'd attire"; she is Sebastian's lost twin sister, and she can prove it by taking them to the home of a sea captain who knows of her disguise and is keeping her women's clothes for her; however, they must produce Malvolio because he has been holding the sea captain imprisoned.
Sebastian turns to Olivia and tells her that she has been "mistook." Had she married Cesario (Viola), she would "have been contracted to a maid." But he gives her good news also. As her husband, he is a bit of a "maid" himself — that is, he is a virgin ("both maid and man"). Olivia calls immediately for Malvolio; she wants to hear why he has had this sea captain imprisoned, and she asks that he be specifically brought before her, even though "they say, poor gentleman, he's much distract."
