‘O, beware, my lord, of jealousy; It is the green-eyed monster which doth mock The meat it feeds on’

Iago dresses the warning as friendly advice: be careful, my lord, jealousy destroys the man who feels it. And the monster does not simply eat its victim. It mocks ‘the meat it feeds on’, toying with the jealous man the way a cat toys with what it catches. Othello himself is the meat.

Green already meant envy and sickness to Shakespeare’s audience, and he had used the colour this way before: Portia speaks of ‘green-eyed jealousy’ in The Merchant of Venice, Act 3 Scene 2.

What makes the line famous is who says it. Iago warns Othello against jealousy in the same conversation in which he is carefully injecting it. It sounds like a friend’s caution and works like a dose.

This comes from Act 3 Scene 3, moments after Iago has set Othello worrying with ‘men should be what they seem’. By the end of the scene Othello is plotting Desdemona’s death. No proof of anything has been shown to him.

‘Jealousy is the green-eyed monster’ is a tidy paraphrase, not the line. What Iago says is: ‘O, beware, my lord, of jealousy; / It is the green-eyed monster which doth mock / The meat it feeds on.’