Maybe the letter moved him, For, as I think, they do command him home, Deputing Cassio in his government. (IV.i.225-226)
Heaven truly knows that thou art false as hell. (IV.ii.42)
To whom, my lord? With whom? How am I false? (IV.ii.43)
Haply, for I am black And have not those soft parts of conversation That chamberers have, or for I am declined Into the vale of years -yet that's not much- She's gone, I am abused, and my relief Must be to loathe her. (III.iii.267-271)
In this scene, Othello is reading a letter Lodovico, Desdemona’s cousin, gave to him from the Duke. The Duke requests for Othello to come back to Venice and for Cassio to be governor in Cyprus instead. Othello is already upset because the subject of Cassio is brought up and Othello and Cassio are not on the best terms. Cassio wants his position as Othello’s lieutenant back, but Othello doesn’t want him because Cassio assaulted an important figure. Othello is manipulated by Iago to think that Desdemona and Cassio are having an affair. This scene is important because this conveys another reason why Othello despises Cassio. This is an external conflict (person vs. person) between Othello and Cassio, where Othello is mad that Cassio is taking his place and that he has to return back to Venice. The insinuations that Desdemona is cheating on him with Cassio makes the situation worse. Othello's anger towards Cassio increases because in his mind, Cassio took his position and his wife. His anger can lead to him harming Cassio out of jealousy.
In this scene, Othello and Desdemona are arguing. Othello is falsely accusing her of being unfaithful. Desdemona is confused as to why Othello is accusing her of being unfaithful and denies his accusations, saying that she is faithful. Othello is too manipulated by Iago to believe Desdemona. He continues to call her a whore and a streetwalker. This scene is important because it displays the trust issues Othello has with Desdemona and marks the event of the downfall in their relationship. This is an external conflict (person vs. person) between Desdemona and Othello. Othello is having issues trusting Desdemona, yet he trusts Iago. Othello is convinced that Desdemona definitely cheated on him, so when she denies his accusations, he becomes angrier. This propels the plot because Othello may hurt Desdemona because he is hurt by her “infidelity.” Othello may also hurt Cassio since he is supposedly Desdemona’s other paramour. Othello would want to seek revenge on Desdemona and Cassio. Othello’s anger towards the both of them will help Iago advance in his plan.
In this scene, Othello is by himself. Iago had just hinted to Othello that Desdemona is cheating on him with Cassio. At first, Othello was curious and trying to understand as to what Iago is trying to say. Next, Iago tells Othello that he thinks Desdemona is cheating on him. Othello responds by saying that he would need evidence. Iago then advises that Othello needs to watch Desdemona and Cassio's interactions and further manipulates Othello. Othello becomes doubtful of Desdemona. Othello is now left alone with poisonous thoughts. He already has a low self-esteem and with his wife possibly cheating on him, it becomes lower. This scene is important because Othello portrays his perspective on Desdemona cheating on him with Cassio. The audience can see Othello in a vulnerable moment. This is an internal conflict (person vs. self). Othello feels that he is not good enough for Desdemona. He thinks his race, lack of manners, and his age makes him inferior to be Desdemona's husband. His insecurity and self-doubt allows Iago to manipulate him and turn his insecurity to anger towards Desdemona and Cassio. It also contributes to the downfall of his and Desdemona’s marriage since he believes she is unfaithful.