Jealousy is defined as a feeling of envious resentment of someone or their achievements, in the play Othello Shakespeare demonstrates this emotion abundantly. Through the use of the main characters of the play Shakespeare masterfully, and timelessly presents jealousy, in an attempt to teach to the world the dangers of this emotion. Othello reveals how jealousy can cause one to make irrational decisions. Othello also presents the power jealousy can have on the human mind, limiting one's ability to function. Shakespeare's Othello highlights the corruption of the human mind, suggesting that jealousy is the most destructive human emotion. .
In Othello, Shakespeare uses jealousy to teach various lessons, lessons which are timeless and relevant. One of these ideas brought up in Othello is that jealousy causes people to make irrational decisions, an example of this comes from the very first act where jealousy plays an instrumental role in the decisions made by Iago. When the decision is announced that Michael Cassio would be named lieutenant and Iago, "his Moorship's ancient" (I.i.33), it brings out Iago's "green-eyed monster" (III.iii.166). Consumed with jealousy for Cassio role, and anger for Othello's decision, Iago begins to resort to corrupt methods to achieving his aims. Consumed by the "green-eyed monster" (III.iii.166) Iago irrationally decides to turn Othello against both his lieutenant and his wife, this in an attempt to attain the role of lieutenant for himself and to hurt Othello (I.iii.372-394). Jealousy causes Iago to make decisions that are blind and quite unnecessary, however being under the destructive powers of jealousy he fails to be rational. In the same act another example of jealousy's destructive nature can be seen, this from Roderigo. Throughout the course of the play Roderigo is madly in love with Desdemona, so much so that he will do anything for a chance to win her over.