Shakespeare uses a number of techniques to express the manipulaton of Iago in this scene.
He lies to Othello in a barefaced manner, as we know from earlier context, in which we see Iago slandering Othello to his friend Roderigo, in the first scene of the book, showing that from the outset Iago has been against Othello, and this facade of trying to “help him out” immediately tells us he is not to be trusted.
From what we have already learnt it is apparent that Iago is a classic Machiavellian stereotype; he goes out of his way to upset others, seemingly for little reason other than his own entertainment, and we know that he is set to destroy Othello, hence why he is planting doubt in his mind that his wife Desdemona is cheating on him with Michael Cassio.
He asks Othello the question, “Did Michael Cassio, when you wooed my lady, know of your love?”
Othello replies “He did from first to last. Why dost thou ask?”
And Iago rather cunningly responds with “But for a satisfaction of my thought – no further harm” which translates as “I was just curious, no reason”.
This is clear reverse psychology which is a key symbol of manipulation. He basically wants to innocently plant the idea in Othello’s mind, that he should be concerned about it.
This has clearly worked as Othello responds with a question “why of thy thought?”
This scene includes chaining conversation, but instead of the traditional question and answer format, it is question after question, which is representative of the confusion in Othello’s mind, planted by Iago, it could symbolize his thoughts as they occur, like a subliminal narration.
There is a repetition of the word “honest”, which is a stark contrast, representing the opposite of Iago but yet he is talking about it as if he understands.
It is ironic how he speaks of how he thinks Michael Cassio is not honest, as we know it is the other way round, and that Iago is