Othello Act 3, Scene 3: "The same."
Emilia sets up a meeting between Desdemona and Cassio, in which Desdemona advises him that she will mend his relationship with her husband. Everything that she says to Othello will be of the good and kind and loyal Cassio. Immediately before Iago and Othello enter the citadel, Cassio steals away, as if evading sight. Iago plants jealous seeds in Othello's mind about Cassio's presence with Desdemona. Desdemona then urges her beloved husband to listen and pardon Cassio within three days. Othello agrees, for he repeatedly claims that he would do anything for his dear wife. After the women leave, Iago baits Othello with images of Cassio and Desdemona's intimacy. Othello claims to have no jealousy and that he loves Cassio and believes him to be an honest man. Iago states:
"Oh, beware, my lord, of jealousy!
It is the green-eyed monster, which does mock
The meat it feeds on. That cuckold lives in bliss
Who certain of his fate loves not his wronger;
But O, what damned minutes tells he over,
Who dotes yet doubts, suspects yet fondly loves!" Act 3, Scene 3
Iago claims that he loves Othello so dearly that he must tell him of such unpleasant news. He reminds Othello that Desdemona did lie to her father in order to marry him, so she is in fact capable of deception. He advises Othello to watch Cassio and Desdemona closely and Othello declares his loyalty and love to Iago forever. Iago leaves Othello to contemplate this new unsettling information.
"O, curse of marriage!
That we can call these delicate creatures ours
And not their appetites! I had rather be a toad
And live upon the vapour of a dungeon
Than keep a corner in the thing I love
For others' uses." Act 3, Scene 3
Desdemona enters, concerned about her husband's well-being, for he looks ill. He tells her that he simply has a headache. He pulls out his handkerchief and she drops it on the floor as she moves to aid in his pain. The couple exits as Emilia picks up the napkin. She informs the audience in soliloquy that the handkerchief was the first gift Othello gave to Desdemona and that she treasures it with all her soul. She plans to give it to her husband, Iago, for he will know what to do with it, and claims that all of her actions are to help and serve him. Iago takes the handkerchief from Emilia, who tries to explain its importance to Desdemona. With typical cruelty, he tells Emilia to leave him alone. He plans to plant the napkin in Cassio's room and allow him to find it, giving even more credence to his plan. "The Moor already changes with my poison. / Dangerous conceits are in their natures poisons, / Which at the first are scarce found to distaste, / But, with a little act upon the blood, / Burn like the mines of sulphur" Act 3, Scene 3.
Othello enters, enraged by the news of Desdemona's supposed unfaithfulness. He demands living proof and evidence of such an affair, or he will take grand measures against everyone, including Iago. Iago tells him that when he slept near Cassio, he heard him mention his love for Desdemona in his sleep. He then mentions that he saw Cassio wipe his beard with a handkerchief. Othello now has his supposed proof on two levels and breaks into a fit of rage, vowing his vengeance upon Cassio and Desdemona. Iago vows to kill Cassio within three days, but leave Desdemona alive. Othello makes Iago his lieutenant.