Iago:Othello Act 1, scene 1, 56–65
It is as sure as you are Roderigo,
Were I the Moor, I would not be Iago.
In following him, I follow but myself;
Heaven is my judge, not I for love and duty,
But seeming so, for my peculiar end;
For when my outward action doth demonstrate
The native act and figure of my heart
In complement extern, 'tis not long after
But I will wear my heart upon my sleeve
For daws to peck at. I am not what I am.
The ever-inventive Iago confesses to his dupe Roderigo that he only seems loyal to (only seems to "follow") the Venetian general, Othello. Actually, Iago serves only himself and his "peculiar end," or selfish aims. Discretion is required: in Iago's paranoid world, revealing your true motives makes you a victim. To express outwardly in "complement extern" the "native act and figure" of one's heart is to manifest externally the inmost shape and tendency of one's desires. Doing so, Iago says, soon leads to betrayal; when your heart is displayed so openly, as if upon your sleeve, the "daws" (jackdaws) will accept the invitation to peck away at it.
By admitting to his treachery, Iago would seem, in effect, to "wear his heart on his sleeve" for Roderigo. Yet, while Iago tells the truth, he doesn't tell all of it, and keeps hidden his true "native act and figure"—his intention to dupe Roderigo out of even more jewels and cash.