I'm Iago. I like destroying people's lives for no apparent reason, which is why I've decided to make Othello think his wife is cheating on him. Sounds like fun to me. And you know what I think?

Who Said It and Where

You don't get to be one of the most notorious and mysterious villains of all time without getting your hands dirty. Just ask Iago. He spends all of his time plotting against Othello and Desdemona. He eventually convinces Othello that his wife has been cheating, despite the fact that Desdemona has been completely faithful.

Why? The truth is we don't really know. Sure, he lost out on a promotion (boo-hoo). And there may or may not be rumors going around town about his wife being promiscuous. But Iago's capacity for cruelty seems limitless. No motivation he gives for his actions seems enough to explain the incredible destruction he wreaks on the lives of the people he knows best.

In this scene, Iago's torture of Othello finally takes hold of the general. He's told us (the audience) what he plans to do, but this is when he actually does it. He lays down the bait. Iago starts asking Othello fake-casual questions about Cassio, a soldier who was often a go-between when Othello courted Desdemona.

Iago keeps dropping uncomfortable hints, and finally, Othello takes the bait. He demands to know what's bothering him. Iago says he'd rather not say, and then Othello presses him some more, and then Iago says he'd rather not say, and Othello presses him again and again.

This pattern continues and by the end of their exchange, Iago has successfully

• cast doubt on Cassio's honesty.
• suggested he is disloyal.
• hinted that Desdemona is unfaithful. 
• warned Othello not to be jealous.

Othello swears he's not the jealous type. He only ever builds his conclusions after investigating his suspicions. If something seems wrong, he'll find out what's happening right away and resolve the situation. He promises he has to see something to raise his suspicion before he'd have doubts about his wife's loyalty.

In response, Iago essentially says, "Okay, if you promise you won't be jealous, you should watch Desdemona with Cassio, but objectively, and not out of jealousy." Iago adds helpfully that Desdemona did deceive her father in order to marry Othello. He's implying that Desdemona is not to be trusted, as she is a woman, and thus a liar. Right.

Othello is persuaded by what Iago has said, and it's clear the seed of suspicion has been planted. Iago tells Othello that he hopes he hasn't ruined his day, which is the trickiest, most dastardly bit of all, because he totally hopes he has ruined Othello's day. Who's a liar now?