Villain, be sure thou prove my love a whore,
Be sure of it; give me the ocular proof:
Or by the worth of man’s eternal soul,
Thou hadst been better have been born a dog
Than answer my waked wrath!

– William Shakespeare

Othello, Act 3, Scene 3. Othello demands that Iago gives him visual proof of his wife’s supposed adultery. As far as Othello is concerned, at least at this stage, the alleged crime has to be seen before he will believe it. Iago of course offers no proof but continues to use insinuation, innuendo and the handkerchief given to Desdemona to plant suspicion into Othello’s mind.