Heart on my sleeve
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.