This book is a perfect treatment of jealousy. In all its intricate mechanics.
Iago, the central agent to stir jealousy, does so without a cause, just like jealousy itself. He feels overlooked for the post as a lieutenant and also hints that his wife had cheated on him with Othello – but these motifs only play a minor role over the play.
Desdemona’s conversation support that point: „Desdemona: Alas the day, I never gave him cause! / Emilia: But jealous souls will not be answer’d so; They are not ever jealous for the cause, / But jealous for they’re jealous: it is a monster / Begot upon itself, born on itself.“ (Shakespeare, 2011, p. 87).
And also Iago is admitting it himself: „Iago: `Twas mine, `tis his, and has been slave to thousands; / But he that filches from me my good name / Robs me of that which not enriches him, / And makes me poor indeed.“ (Shakespeare, 2011, p. 67).
And most famously: „O, beware, my lord, of jealousy, / It is t he green-eyed monster which doth mock / The meat it feeds on.“ (Shakespeare, 2011, p. 67).
One central theme as a cause for jealousy in the book is deception – sometimes real, sometimes imagined, but the effect on jealousy is the same. Iago declares openly right at the beginning that he deceives: „But I will wear my heart upon my sleeve / For daws to peck at: I am not what I am.“ (Shakespeare, 2011, p. 4).
And once deception and accusation set the foundation for jealousy, it grows upon itself
For example: Othello does not react to the first accusations that his wife is cheating on him. But Iago knows that time helps suspicions and finally jealousy to grow: „After some time, to abuse Othello’s ear / That he is too familiar with his wife. (...).... hell and night / Must bring this monstrous birth to the world light.“ (Shakespeare, 2011, p. 29).
Once the seed of doubt is sown, whatever the suspected do, it will look like further proof of jealousy: „Iago: And what’s he then, that says I play the villain? / (...) How am I, then, a villain / To counsel Cassio to this parallel course, / Directly to his good? Divinity to hell! / When devils will the blackest sin put on, / They do suggest at first with heavenly shows, / As I do now: for whiles this honest fool / Plies Desdemona to repair his fortunes, / And she for him pleads strongly to the Moor, / I’ll poor this pestilence into his ear, - / That she repeals him for her body’s lust; / And by how much she strives to do him good, / She shall undo her credit with the Moor. / So will I turn her virtue into pitch; / And out of her own goodness make the net / That shall enmash them all.“ (Shakespeare, 2011, p. 255.
„Iago: Trifles light as air / Are the jealous confirmations strong / As proofs of holy writ.“ (Shakespeare, 2011, p. 73).
Once jealousy is growing, it blurs the line between knowing and doubting:
„Othello: Why, why is this? / Think’st thou I’d make a life of jealousy, / To follow still the changes of the moon / With fresh suspicions? No, to be once in doubt / Is once to be resolv’d. (...) No Iago; / I’ll see before I doubt.“ (Shakespeare, 2011, p. 68).
Not knowing anymore what is real and what imagined, makes a person lose his characrer: Thus the play ends, by Othello blurring the line and almost losing his identity:
„Lodovico: Where is this rash and most unfortunate man? / Othello: That’s he that was Othello; - here I am.“ (Shakespeare, 2011, p. 141).