Why+is+Iago's+plan+being+implemented+so+perfectly?

Tsechu: I think Iago is a very clever character who has studied the human nature very well. Because of his intelligence he is able to construct plans which he knows humans will fall into due to their nature. He knows Desdemona, Othello, Cassio and Roderigo, characters and he knows how they will react to his comments and insights.

Molly- I think Iago's plan is working so well because it is a fictional play written by William Shakespeare (or so we think). In a fictional story the writer is free to do as he or she wishes. Iago's plan is being implemented so perfectly because Shakespeare wanted it to.