Part of how Iago is able to manipulate Othello, and most others in the play, is his complete understanding of internal motivation and understanding of others. Iago reads and understands many of the characters in the play rather well. He knows very well where Othello's internal weaknesses lie and he is able to exploit them in manipulating Othello into doing what he wants him to do. The notion of jealousy that lies inside Othello is something that Iago uses to bring down the mighty warrior. Understanding that this might be due to the fact that Othello is an outsider, of a different religion, and of a different ethnicity, Iago is able to identify that Othello, for all his greatness, is extremely scared and insecure about losing everything. Reading this well, Iago is able to understand that this doubt is what lies at the heart of all of Othello's success. Striking at it in different ways is what allows Othello to be manipulated.