Here, Iago's purpose becomes plain; he sees that Othello and Desdemona's marriage is less than solid, and seeks to use his powers to break this marriage apart. Iago is again "honest" about his intent, but only to a person whose involvement will help him greatly. The words "honest" and "honesty" appear repeatedly in the play, used primarily by Iago, or in reference to him; ironically, Iago is the only person in the play whom Othello trusts to judge who is and is not honest, and the only one whose integrity is not questioned until it is too late.
Iago's battle against Othello and Cassio certainly counts as an embodiment of this theme. Iago and his evil battle to corrupt and turn the flawed natures of other characters, and he does succeed to some extent. By the end of the play, neither has won, as Desdemona and Emilia are both dead, and Iago revealed and punished. Othello is a tragic character, but one that is neither good nor evil. His flaws are easily manipulated, and he is unable to see the truth while blinded by pride. He is a good soldier and a good man, but this good is twisted and he commits an evil act.