| Quote #10
After Cassio gets into a drunken brawl and loses his position as Othello's officer, he worries about the loss of his "reputation," which is tied up in his military service and his public behavior. Cassio feels that, without his "reputation" as an upstanding soldier, he's nothing more than a "beast."
| Quote #11
for whiles this honest fool
Earlier, we saw how Cassio sees his "reputation" as being the sum of his public behavior and his military service. Here, we can see that Desdemona's "reputation" hinges on her fidelity to her husband. When Iago says he's going to ruin Desdemona's "credit with the Moor," he means he's going to tarnish her reputation as a loyal wife ("turn her virtue into pitch").
| Quote #12
Iago emphasizes that his real thoughts and feelings cannot be known by anyone—not Othello and not even the audience.