It’s about lying.
English literature provides many studies of human evil, but perhaps the most poignant and appalling of all is Iago, Shakespeare’s villain of the Tragedy of Othello. Iago provides us with an examination of St. Thomas Aquinas’s claim that lying remakes a person into the very image of the devil. Iago is held by literary historians as possibly the most purely evil character in English literature whose calculated and ruthless manipulations bring about ruin and death for all around him. And he accomplishes all this by lies and the presentation of a false front of virtue, a “heavenly show”.