I know not that; but such a handkerchief—­
     I am sure it was your wife’s—­did I to-day
     See Cassio wipe his beard with.

‘If it be that,’ he answers—­but what need to test the fact?  The ‘madness of revenge’ is in his blood, and hesitation is a thing he never knew.  He passes judgment, and controls himself only to make his sentence a solemn vow.

The Othello of the Fourth Act is Othello in his fall.  His fall is never complete, but he is much changed.  Towards the close of the Temptation-scene he becomes at times most terrible, but his grandeur remains almost undiminished.  Even in the following scene (III. iv.), where he goes to test Desdemona in the matter of the handkerchief, and receives a fatal confirmation of her guilt, our sympathy with him is hardly touched by any feeling of humiliation.  But in the Fourth Act ‘Chaos has come.’  A slight interval of time may be admitted here.  It is but slight; for it was necessary for Iago to hurry on, and terribly dangerous to leave a chance for a meeting of Cassio with Othello; and his insight into Othello’s nature taught him that his plan was to deliver blow on blow, and never to allow his victim to recover from the confusion of the first shock.  Still there is a slight interval; and when Othello reappears we see at a glance that he is a changed man.  He is physically exhausted, and his mind is dazed.[100] He sees everything blurred through a mist of blood and tears.  He has actually forgotten the incident of the handkerchief, and has to be reminded of it.  When Iago, perceiving that he can now risk almost any lie, tells him that Cassio has confessed his guilt, Othello, the hero who has seemed to us only second to Coriolanus in physical power, trembles all over; he mutters disjointed words; a blackness suddenly intervenes between his eyes and the world; he takes it for the shuddering testimony of nature to the horror he has just heard,[101] and he falls senseless to the ground.  When he recovers it is to watch Cassio, as he imagines, laughing over his shame.  It is an imposition so gross, and should have been one so perilous, that Iago would never have ventured it before.  But he is safe now.  The sight only adds to the confusion of intellect the madness of rage; and a ravenous thirst for revenge, contending with motions of infinite longing and regret, conquers them.  The delay till night-fall is torture to him.  His self-control has wholly deserted him, and he strikes his wife in the presence of the Venetian envoy.  He is so lost to all sense of reality that he never asks himself what will follow the deaths of Cassio and his wife.  An ineradicable instinct of justice, rather than any last quiver of hope, leads him to question Emilia; but nothing could convince him now, and there follows the dreadful scene of accusation; and then, to allow us the relief of burning hatred and burning tears, the interview of Desdemona with Iago, and that last talk of hers with Emilia, and her last song.