Not the unjust suspicions of Othello, not Iago’s treachery, place Desdemona in a more amiable or interesting light than the casual conversation (half earnest, half jest) between her and Aemilia on the common behaviour of women to their husbands.  This dialogue takes place just before the last fatal scene.  If Othello had overheard it, it would have prevented the whole catastrophe; but then it would have spoiled the play.

The character of Iago is one of the supererogations of Shakespeare’s genius.  Some persons, more nice than wise, have thought this whole character unnatural, because his villainy is without A sufficient motive.  Shakespeare, who was as good a philosopher as he was a poet, thought otherwise.  He knew that the love of power, which is another name for the love of mischief, is natural to man.  He would know this as well or better than if it had been demonstrated to him by a logical diagram, merely from seeing children paddle in the dirt or kill flies for sport.  Iago in fact belongs to a class of characters common to Shakespeare and at the same time peculiar to him; whose heads are as acute and active as their hearts are hard and callous.  Iago is, to be sure, an extreme instance of the kind; that is to say, of diseased intellectual activity, with an almost perfect indifference to moral good or evil, or rather with a decided preference of the latter, because it falls more readily in with his favourite propensity, gives greater zest to his thoughts and scope to his actions.  He is quite or nearly as indifferent to his own fate as to that of others; he runs all risks for a trifling and doubtful advantage; and is himself the dupe and victim of his ruling passion--an insatiable craving after action of the most difficult and dangerous kind.  ‘Our ancient’ is a philosopher, who fancies that a lie that kills has more point in it than an alliteration or an antithesis; who thinks a fatal experiment on the peace of a family a better thing than watching the palpitations in the heart of a flea in a microscope; who plots the ruin of his friends as an exercise for his ingenuity, and stabs men in the dark to prevent ennui.  His gaiety, such as it is, arises from the success of his treachery; his ease from the torture he has inflicted on others.  He is an amateur of tragedy in real life; and instead of employing his invention on imaginary characters, or long-forgotten incidents, he takes the bolder and more desperate course of getting up his plot at home, casts the principal parts among his nearest friends and connexions, and rehearses it in downright earnest, with steady nerves and unabated resolution.  We will just give an illustration or two.

One of his most characteristic speeches is that immediately after the marriage of Othello.

   Roderigo.  What a full fortune does the thick lips owe,
     If he can carry her thus!