How does Iago's envy contribute to the downfall of Othello?

It is Iago's envy that causes him to hatch his scheme to destroy Othello. This scheme forms the basis for the entire plot. The audience discovers in the first scene of the play that Othello has passed over Iago for a promotion, choosing instead to promote Michael Cassio. Iago and Rodrigo go to Brabantio's house (Brabantio is Desdemona's father) to tell him that Othello and his daughter are sleeping together. This, it turns out, is...

It is Iago's envy that causes him to hatch his scheme to destroy Othello. This scheme forms the basis for the entire plot. The audience discovers in the first scene of the play that Othello has passed over Iago for a promotion, choosing instead to promote Michael Cassio. Iago and Rodrigo go to Brabantio's house (Brabantio is Desdemona's father) to tell him that Othello and his daughter are sleeping together. This, it turns out, is just the beginning of Iago's scheming. In a soliloquy to end the scene, he resolves to "show out a flag and sign of love" to the Moor, though he says he hates him as he does "hell-pains." Iago's jealousy and scheming sets in motion a series of tragic events that consume Othello, his innocent wife Desdemona, Iago's wife Emilia, and others. Iago's scheme is so vicious and cunning that it seems entirely out of proportion to the grievance that he airs at the beginning of the play.