Discuss the significance of the phrase "I am not what I am" in Othello.
In this quote Iago is clarifying to Roderigo that he is merely pretending to be a loyal underling to Othello, and in actuality is only looking out for himself. Iago is getting Roderigo to trust him by convincing him that he also hates Othello. Although Iago does truly seem to hate Othello, he has another reason for bonding with Roderigo. Iago plans on using Roderigo to help destroy Othello, and thus he requires that both men trust him implicitly.
However, this line of Iago's is much more than an attempt to win over Roderigo. This quote sets the backdrop for all of Iago's evil deeds and explains why people continuously have faith in him. Iago is terribly good at playing whatever role he must, even if it is demeaning, in order to carry out his disastrous plans.
In addition, this line foreshadows the rest of the play, particularly the ending. Ironically, Iago contrasts himself to Othello by saying that he doesn't wear his heart on his sleeve as Othello does, but rather he hides his true nature. However, this line turns out to be somewhat untrue because Othello also reveals himself to be something other than what he'd been proclaiming. Othello has an intense self-righteousness that gets him out of some messes, but eventually dooms him completely. Despite the moral superiority that he professes to have, he gives way to destructive jealousy and distrust. If Othello had truly been a righteous man, then he would have had faith in his wife Desdemona, who he was supposed to love without condition, and wouldn't have killed her. Instead, he commits murder, a serious crime that such a "good" man should have been incapable of, and then kills himself.
Ultimately, it turns out that declaration that Iago so proudly states "I am not what I am" is indicative of both himself and the man he despises so very much.