He then approaches the idea that Othello, whom he has convinced Roderigo to regard as worthless, is in need of replacing with a suitable successor. As with most of Iago's manipulative speeches he shifts into a more complex manner of speech often to invoke emotion in the person he is trying to influence. He also tends to shift into prose rather than verse fitting the fact that he is usually conspiring. With Roderigo he plants several ideas that Othello is overly aristocratic and does not correspond with the 'vernacular' of the time period even for a man in his position as general. He shows this by mocking Othello's voice and accent, which suggests his high (or elevated?) social status. Iago's aim is to invoke passion in Roderigo in order to convince him that Othello has in fact gone too far. Additionally, the phrase 'bombast circumstance' demonstrates Iago's views on Othello's social status.
Iago and Roderigo find common ground with their mutual racist views on Othello and black people in general. For example, when Iago uses the word Moor in 'his Moorship's ancient!' this racist remark is using Othello's descent and ethnicity to suggest that he is unsuitable for the position he currently holds. Furthermore, by harnessing Roderigo's anger towards Othello he is able to direct it away from himself and so Roderigo seems to forget how he felt about Iago in the opening scene of the play. The manipulation of Roderigo demonstrates how Iago can convert a wealthy, powerful man like Roderigo into a man who is willing to aid Iago in his conspiracy to overthrow Othello.
Another aspect of how Iago is portrayed in the first act of the play is his attitude towards Cassio and how it compares to his attitude towards Othello as well as how he acts differently both in and out of their presence. Shakespeare makes it clear how Iago feels about Cassio's placement as Othello's lieutenant. He calls him a great 'arithmetician', which although is a compliment in some ways highlights the fact that he is a man who knows no 'more than a spinster' when it comes to war and has next to no experience on the battlefield.