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 pour 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 I will turn her virtue into pitch,
And out of her own goodness make the net
That shall enmesh them all.
As is sometimes true in Shakespeare, Othello is not really the main character of his title tragedy. The tragedy, to be sure, is his, but we are never so close to him as we are to Iago, who is nearly as accomplished a soliloquist as Hamlet, and who dominates the play. Othello himself is, as A. C. Bradley points out, "the most romantic figure among Shakespeare's heroes" and becomes something like a ruined fairytale, distantly horrific, while we hew more closely to his destroyer. This is, I think, the genius stroke of Othello: Nowhere else in Shakespeare, even in Macbeth, are we so close to evil.
The guiding sentiment of the play is jealousy. It is not, at first, Othello's; he is, as he says at the end, "not easily jealous." But Iago harbors a deep jealousy for Cassio, Othello's newly chosen lieutenant, and it is this jealousy which he manages to push, like a disease-carrier or an accomplished politician, on to Othello. Conventional wisdom holds that Iago has no motivation for his jealousy, but as I read it, Iago has several, including the fact that Othello passed over Iago for Cassio's position and that Iago has suspected Cassio of sleeping with his wife, Emilia. At one point, Iago makes this startling statement:
If Cassio do remain
He hath a daily beauty in his life
That makes me ugly...
I find this fascinating--Iago, who has chosen evil as his good and constantly touts the power of his will, retains a deeply held jealousy for those who make the opposite choice.
The creature that Iago reduces Othello to is like Iago in the seething bitterness of its envy, but in its shallowness and foolishness it resembles also Iago's companion Roderigo, who is deeply in love with Othello's wife, Desdemona. There is some irony to the spectacle of Othello, the romantic warrior-prince, reduced to insanity at the idea that his wife is not his completely:
I had rather be a toad
And live upon the vapour of a dungeon
Than keep a corner in the thing I love
For others' uses.
What is most frightening about Othello is that Othello--just, valiant, accomplished, romantic--is turned into a weapon against himself--
No, my heart is turned to stone. I strike it and it hurts my hand.
--not through any flaw of his own, but because he is overpowered by a stronger will. In any other play, Othello should have towered over every other character, but his misjudging of Iago extends not only to his dishonesty but also his immense intelligence and power. I would venture to say that Iago is the strongest of all personalities in Shakespeare, and that no one but he could have left behind the ruin that he does, extending even to himself. He is like the witches of Macbeth, but more frightening because he is more human.