The cavalier attitude with which Gloucester dismisses Edmund's paternity further reinforces the difference between Edmund and Edgar. Where Edgar is entitled to his father's name, his title, and his property, Edmund is entitled to nothing but the coarse jesting that accompanied his conception.
Gloucester ignores any possibility that his youngest son may resent this easy dismissal of both Edmund's birth and his future prospects, but Edmund finds in his father's thoughtless words a reason to destroy Gloucester. In plotting his revenge, Edmund reveals that he is a worthy opponent, even though much of his desire for revenge is an emotional response to Gloucester's words. In Shakespeare's Othello, Iago makes sport of his actions while proving himself superior intellectually to those around him. In comparison, Edmund reacts to his situation with seriousness and reason, but his actions never stem from a need to make sport.
Language is particularly noteworthy in this scene. Shakespeare weaves in much talk of seeing, although Gloucester does not truly see until he is blinded later in the play. Gloucester says that if Edmund's letter contains nothing significant, then "I shall not need my spectacles" (I.2.35). But, of course, even with spectacles, he cannot see that Edmund is deceiving him. After exclaiming "let's see, let's see" (I.2.42), he shows that he can neither recognize the dishonestly in what he reads nor see that Edmund is lying. In mistaking Edmund's motives, Gloucester is already blind to the evil events unfolding around him.
Edmund condemns his father's age in the forged letter by suggesting that old men should step down and give control to those who are younger. Gloucester is referred to as an aged tyrant who desires to maintain control in order to keep his sons from receiving their inheritances.
