Edgar, now dressed as a peasant, pretends to lead Gloucester up a steep cliff, while in fact they are going over flat ground. At the "summit" Edgar gives a long speech on "how fearful and dizzy it is to cast one's eyes" (17) over the edge. Taking his bait, Gloucester asks to be led to the cliff and, giving Edgar a purse with a valuable jewel in it, asks him to go away. Edgar does so, and says to himself that he is only playing with Gloucester's despair in this way only in order to cure it.
Showing exemplary dutifulness to his father, Edgar encourages him to believe one further illusion, which, however, should cure him of his woes. On stage, Edgar's description of the huge hill where there is none sounds, however, almost as deluded as Lear's mad ravings.
Standing at the "edge" of the nonexistent cliff, Gloucester address the "mighty gods": he is renouncing the world "in [their] sights" and that if he could bear their "great opposeless wills" any longer, he would live out his life (44-8). However, since he cannot, he asks them to bless Edgar. Then he "leaps"—falling to the ground in a faint. Edgar now pretends to be a new person who saw Gloucester leapfrom the "cliff," and approaches Gloucester. Although Gloucester asks to be left alone, Edgar refuses: he keeps telling Gloucester that it is a miracle that he has survived his fall and persuades Gloucester that the creature that led him to the edge of the cliff was in fact the devil. "The clearest gods," Edgar tells his father, "have preserved thee" (90-1).
Even though he has suffered so much, Gloucester still believes that a divine order exists. Speaking of the world in the gods' "sights," he further describes them as spectators who have the ultimate insight into human affairs. When Edgar approaches him after the "fall," he, too, describes the gods as looking out for humans.
Lear enters, raving and mad. Edgar cannot help but exclaim in grief at his appearance: "O, thou side-piercing sight!" (104). Hearing Lear, Gloucester recognizes his voice and calls out to him, asking to kiss the king's hand. Lear, however, continues raving. Cordelia's gentleman and a group of attendants enter. Spotting Lear, they entreat him to come to Cordelia, but he flees. As Cordelia's men pursue Lear, Edgar asks one of the Gentleman for an update. He reports that the battle between the British forces of Edmund, Goneril, and Regan and the French force led by Cordelia is imminent.
Raving mad, Lear fulfills his own worries before the storm and the prophecy of the Fool in 1.4 that he would become like a Fool playing word games. Edgar sees Lear's madness as a symbol of the current dissolution of Britain. The imminent battle indicates that that dissolution, in one form or another, is about to come to a head.
Gloucester begs the "ever-gentle gods" (241) for forgiveness for his attempted suicide. Edgar approaches him. As he takes Gloucester's hand, however, Oswald appears. Rejoicing to have spotted the "eyeless head" (254) of Gloucester—who Regan bid him to kill in 4.5—he draws his sword. Edgar intercedes, still in the persona of a peasant. Puzzled that a peasant would risk himself for a traitor, Oswald orders Edgar to stand down. They fight; Edgar kills Oswald. As he dies, he asks Edgar to take the money in his purse and bury him, and take the letters therein and deliver them to Edmund, Earl of Gloucester.
Right after Gloucester has evoked the gods as spectators and protectors, Edgar is brave enough to stand up and defend his father, despite his father's former misjudgment and mistreatment of him. In his selflessness, Edgar's actions parallel Cordelia's. The self-interested and ambitious Oswald, failing to recognize Edgar, is puzzled by his gesture of selfless devotion.
Edgar opens Oswald's purse and reads the letter in it—which is from Goneril to Edmund, attempting to persuade him to murder Albany and marry her. Shocked, Edgar resolves to head off and find the "murderous lechers" (304) Edmund and Goneril, and eventually to reveal all to Albany. He approaches Gloucester, who has been privately grieving to himself, and, calling him "father," takes his hand and leads him away.
The coincidental confrontation with Oswald gives Edgar insight into all the machinations taking place between Lear's children, as their personal allegiances fall apart in the political chaos they have created. But, meanwhile, Edgar has now revealed himself to his father, restoring that family bond.