Before the two men part, Iago goes to further pains to make Othello believe in his honesty and also to insure that Othello's jealousy has been sufficiently inflamed. He must also measure how well he has succeeded thus far. Iago stresses that Cassio is his "worthy friend"; in other words, one does not lie about one's friends and, therefore, the Moor must not exaggerate in his imagination what he hears. Yet Iago is certain that Othello has already exaggerated to himself everything he has just heard. For that reason, Iago's remark to Othello that all this has "a little dash'd your spirits" (214) is a gross understatement. Othello is no longer as sure as he was of Desdemona's fidelity, for he ponders on the possibility of " . . . nature erring from itself — " (227). This thought is similar to his father-in-law's observation in Act I, Scene 2, when Brabantio spoke of "nature erring" — when Desdemona "unnaturally" chose Othello, a man not of her own race or culture. Othello turns and asks that Iago's wife, Emilia, watch Desdemona closely. Then he bids Iago farewell, painfully asking himself why he married at all; it is obvious to him that "this honest creature [Iago] doubtless / Sees and knows more, much more, than he unfolds" (242–243).
Now we hear Othello in a soliloquy (258–277), and the range of the imagery he uses underscores the appalling change in his character. There is only one thing now of which Othello is certain — the "exceeding honesty" of Iago. The Moor is obsessed with the need to prove or disprove Desdemona's fidelity. If he indeed finds her false, he'll "whistle her off and let her down the wind / To prey at fortune" (262–263) — that is, he will turn her out and make her shift for herself. And here he begins to look for reasons for her unfaithfulness. Convulsed with introspection, he curses his black skin and his lack of social graces and also the fact that he is "into the vale of years" (266) (he is much older than Desdemona) — all these things, he fears, could turn a woman from her husband's bed.
