And his unbookish jealousy must construe
Poor Cassio’s smiles, gestures and light behavior,
Quite in the wrong.
– William Shakespeare
Othello, Act 4, Scene 1. Iago exploits Othello’s nature to his advantage in order to fire up his jealousy to the extreme. His plan is to talk to Cassio about his girlfriend Bianca, while Othello hiding nearby thinks Cassio is talking about Desdemona.