It focuses on Iago's words to Othello, «O, beware, my lord, of Jealousy. It is the green-eyed monster.» in act 3, scene 3 and just how important this warning was not only for Othello, but also for Roderigo and for Iago.
Before considering the importance of Iago's words, it is important to define what jealousy means. According to The New Lexicon Webster's Encylopedic Dictionary of the English Language, «jealousy is a state of fear, suspicion, revenge or envy caused by a real or imagined threat or challenge to one's possessive instincts. It may be provoked by rivalry, in sexual love, by competition or by desires for the qualities or possessions of another.»
Roderigo is foolish and even at times unusually feeble-minded. This explained partially by Roderigo's jealousy: he is infatuated with Desdemona and has been for some time. He is willing to do anything to win her love. He is jealous that Desdemona loves Othello and not him. In accordance with the definition of jealousy, Roderigo desires the possessions of another. It is this jealousy which moves him to do many evil things in the play. He pays Iago large amounts of money to conjure up a scheme to acquire Desdemona. He gives in to Iago at the beginning of the play. In effect he has become the villian's disciple. By doing this, he himself has adopted the green-eyed monster image. In act two, he is prompted by Iago to cause a commotion and begin a fight with Cassio. Later in act four, scene two, Roderigo is convinced by Iago to kill Cassio. In act five, scene one, Roderigo attempts to kill Cassio but only manages to wound him. At the same time Cassio wounds Roderigo. Iago (who was watching this fight) leaves only to re-enter later and kill Roderigo. Roderigo's jealousy brought upon his downfall.
Most people do not think of jealousy as Iago's downfall, but in essence, jealousy has many negative effects on Iago. By using Iago, Shakespeare has shown just how powerful jealousy really is. Iago is cunning, crafty, intellectual and intelligent. Despite seeming to be impermeable to negative emotions such as jealousy, the exact opposite seems to happen. Iago can not accept the fact that Othello overlooks him and appoints Cassio as his lieutenant. Iago finds it appalling and is jealous that he wasn't promoted. Iago fits the definition of jealousy because he is in a state of revenge which is provoked by competition. This jealousy made Iago the villian or as was put in the play, «the green-eyed monster.» The play focuses on his plot to ruin Othello because he wasn't chosen.
Near the end of the first act, Iago explains to Roderigo that Othello and Desdemona will be undone by his wit. As he states it, separating Othello and Desdemona becomes a challenge to him and the forces of evil:
If sanctimony and a frail vow betwix an erring barbarian
And a supersublte Venetian be not too hard for my wits
And all the tribe of hell, thou shalt enjoy her.
Iago uses his wit, his scheming or cunning, to make Cassio lose his credibility in Othello's eyes, initially by coercing Cassio to lose control at the party and begin to fight. Then by making it appear that Desdemona is having a secret romance with Cassio. But in the end, minor errors (but very important errors) contributed to his downfall. The first being that Roderigo was unable to kill Cassio and the second being his wife, Emilia, who in the end can no longer keep quiet and lets Othello know that he has been deceived by Iago. From this point on, there was a different view of Iago. He could no longer uphold his «honest Iago» image. He was now evil Iago. Perhaps Iago's plan would have been successful if he wasn't so persistent in destroying Othello and Desdemona. He was already successful with destroying Cassio's reputation and his own reputation was improving drastically. Jealousy and his thirst for power made him continue and ultimately lead to his failure.
Out of all the characters in this play, it is most obvious that jealousy was what ruined Othello. Jealousy has the most profound effect on Othello. Of course, it is Iago who plants vivid pictures of Desdemona and Cassio sleeping together in Othello's head. However, Othello is a simple man. He has never had to deal with this type of situation. As a result, he had very extreme reactions because of his jealousy. Othello tells Iago that he wants Iago to kill Cassio and that he will kill Desdemona. His love for Desdemona is so strong and still jealousy overpowers him. Jealousy has made him lose his ability to reason or think logically. In fact, Iago has been so successful with his plan that he was able to put Othello into a state of madness. He even loses control of his body and Iago explains it as epileptic seizures.
At the end of the play, after Othello smothers Desdemona to death, it is brought to his attention that he was set up by Iago. In horror, he realizes his mistake. Just before his suicide, Othello explains that all will have to refer to him as «one that loved not wisely but too well» (act five, scene two, line 344). His lack of experience brought upon his ruin.
One of the stylistic devices in Othello is the way in which Shakespeare's presentation of jealousy is made almost equivalent to that emotion. In other words, jealousy is described throughout the play as a monstrous emotion that becomes increasingly more destructive and intense. As jealousy is always growing, so does Shakespeare's presentation of jealousy grow throughout the play. Shakespeare's attention to jealousy is slight in the opening act., Then in act two, jealousy moves swiftly to centre stage and stays there the rest of the play.