Original: Alas, thrice-gentle Cassio!
Modern: Oh no, my dear, sweet Cassio!

Original: My advocation is not now in tune;
Modern: My ability to speak up for you isn’t working right now;

Original: My lord is not my lord; nor should I know him,
Modern: My husband isn’t acting like himself; I wouldn’t even recognize him

Original: Were he in favour as in humour alter’d.
Modern: if his appearance had changed as much as his mood has.

Original: So help me every spirit sanctified,
Modern: I swear by all the holy spirits,

Original: As I have spoken for you all my best
Modern: that I have defended you with everything I have

Original: And stood within the blank of his displeasure
Modern: and put myself directly in the path of his anger

Original: For my free speech! you must awhile be patient:
Modern: because I spoke honestly! You must be patient for now:

Original: What I can do I will; and more I will
Modern: I’ll do whatever I can; in fact, I’ll do more

Original: Than for myself I dare: let that suffice you.
Modern: than I would dare to do for myself: let that be enough for you.

In Act III, scene iii of Othello, Iago continues his manipulation of Othello by planting seeds of suspicion about Desdemona’s fidelity. When Othello demands proof of his wife’s alleged infidelity, Iago claims he has witnessed Cassio talking in his sleep about Desdemona, describing intimate encounters with her. Iago also mentions seeing Cassio wipe his beard with a handkerchief that he believes belongs to Desdemona - the very handkerchief that Othello had given to his wife as their first gift. This supposed evidence inflames Othello’s jealousy and convinces him of Desdemona’s guilt.

By the end of the scene, Othello’s transformation from loving husband to vengeful murderer is nearly complete. He vows revenge against both Desdemona and Cassio, kneeling alongside Iago in a mock-sacred oath of loyalty and vengeance. Iago pledges to help Othello carry out his revenge, and Othello promotes him to lieutenant, the position that Cassio had previously held. The scene concludes with both men committed to a course of action that will lead to the tragic events of the play’s final acts, with Othello now fully under Iago’s influence and believing in his wife’s betrayal.

Othello opens in Venice, where the Moorish general Othello has secretly married Desdemona, the daughter of the Venetian senator Brabantio. When Iago, Othello’s ensign who harbors deep resentment for being passed over for promotion in favor of Cassio, reveals this marriage to Brabantio, the senator accuses Othello of using witchcraft to seduce his daughter. However, when the Duke of Venice summons Othello to lead the Venetian forces against a Turkish invasion of Cyprus, Desdemona herself testifies that she married Othello willingly out of love. The Duke dismisses Brabantio’s charges, and Othello departs for Cyprus with Desdemona, Iago, and his officers.

Once in Cyprus, the Turkish fleet is destroyed by a storm, but Iago begins executing his plan for revenge. He manipulates Cassio into a drunken brawl that results in Cassio’s demotion, then convinces Cassio to seek Desdemona’s help in regaining Othello’s favor. Iago uses these innocent meetings between Desdemona and Cassio as evidence to plant seeds of jealousy in Othello’s mind, suggesting that his wife is having an affair with the former lieutenant. To strengthen his deception, Iago arranges for Othello to overhear him speaking suggestively with Cassio about Bianca, Cassio’s mistress, while Othello believes they are discussing Desdemona.

The manipulation reaches its climax when Iago obtains Desdemona’s handkerchief—Othello’s first gift to her—through his wife Emilia, who serves as Desdemona’s attendant. Iago plants the handkerchief in Cassio’s chambers and later shows it to Othello as proof of the affair. Consumed by jealousy and convinced of Desdemona’s infidelity, Othello smothers her in their bed. When Emilia discovers the murder, she reveals Iago’s treachery before he kills her. Othello, realizing he has murdered his innocent wife, stabs himself and dies beside Desdemona. Iago is arrested, Cassio is appointed to govern Cyprus, and Iago is taken away to face torture and execution for his crimes.