If Shakespeares purpose (theme) in writing Othello was to explore and demonstrate Machiavellis ideas, how does he use the character of Iago to do so?

Plan and compose an analytical essay to answer this question by selecting at least three (3) scenes from the play that BEST show Iagos moving others toward a particular end through the use of: 
Virtu (Masterful use of Fortuna and Necesita).
The motivations of other characters.
Ethos, pathos, and/or logos in speech. 
For each scene you select for analysis, be sure to identify each of the above elements and use ample cited textual evidence for support.