In Othello, Iago plants seeds of doubt and jealousy in Othello. Iago convinces Othello that his beautiful wife Desdemona and Cassio are having an affair. Iago assures Othello that he will kill Cassio for what he has done. When Cassio and Roderigo are fighting, Cassio slays Roderigo. Then Iago comes from behind and wounds Cassio in the leg. Othello does not see the incident, but he hears Cassio cry out that he is being murdered. In Act V, Scene I, Cassio cries out that he is being murdered:
I am maimed forever. Help, ho! murder! murder!
Othello assumes that Iago has killed Cassio. Othello is convinced that Iago is honest. Iago is a master at manipulation. Iago has convinced Othello that he loves him. For this reason, Othello thinks that Iago has taken revenge on Cassio for having an affair with his wife Desdemona. When Othello hears Cassio scream out that he is being murdered, Othello is touched by Iago's honesty as keeping his word:
The voice of Cassio. Iago keeps his word.
Truly, Othello is thinking the Iago has kept his word in killing Cassio. In turn, Othello thinks he must murder Desdemona for her infidelity. In Act V, Scene II, Othello is talking with Desdemona. He accuses her of having an affair with Cassio. Othello says Cassio has Desdemona's handkerchief and this is proof that she has been unfaithful:
That handkerchief which I so loved and gave you,
You gave to Cassio.
In her defense, Desdemona denies having ever given Cassio her handkerchief. She insists that Othello send for Cassio to refute Othello's accusation. Desdemona declares she would never give her handkerchief to Cassio
No, by my life and soul!
Send for the man and ask him.
Desdemona tries to convince Othello that she has been true to him. She insists that he send for Cassio to ask him if she has given him her precious handkerchief:
I never gave it to him. Send for him to come here.
Let him confess the truth.
Othello states that he Cassio cannot confirm her story because Cassio's mouth has been stopped. Othello is certain that Iago has followed Othello's orders to kill Cassio. Rahter than coming out and stating that Cassio is dead, Othello uses figurative language indicating that Cassio's mouth has been stopped or shut:
No, his mouth is stopped;
Honest Iago has taken orders for it.
Through metaphorical comparison, Othello indicates that Cassio's mouth has been stopped from speaking. He does not directly state that Cassio is dead. However, without coming right out and stating it, Othello is indicating that Cassio is indeed dead.
In fear, Desdemona interprets Othello's figure of speech as Cassio being dead and questions Othello:
O, my fear interprets! What, is he dead?
Believing Cassio is dead and cannot confirm that Desdemona did not give him her handkerchief, Desdemona loses all hope:
Alas, [Cassio] is betrayed, and I have no hope!
Desdemona's fears are realized as Othello smothers her.