Villain, be sure thou prove my love a whore, Be sure of it; give me the ocular proof. (778) Iago. Her honour is an essence that ‘s not seen; They have it very oft that have it not: But, for the handkerchief. (787)
Iago keeps on impelling Othello's jealousy by revealing Othello that he knows Cassio and Desdemona slept together. Hence, it leads Othello falls into an epileptic fit. Additionally, he constantly mentions handkerchiefs, saying that it belongs to Desdemona, and she can give it to anyone she wants. Hence, Othello easily believes Iago's evidence is without a doubt because it is the “ocular proof.” Overall, it leads Othello to a condition of paranoid jealousy and is no longer capable of giving a fair assessment of the situation. Lastly, when Emilia reveals Iago’s plan, we can guess his reaction toward it. A sneaky person does not have the bravery to stand still in front of the court. He definitely refuses any responsibilities in causing the tragedy: Iago. I told him what I thought, and told no more Than what he found himself was apt and true. Emilia. But did you ever tell him she was false? Iago. I did Emilia. You told a lie; an odious, damned lie.