Edgar, disguised as Poor Tom, stands in the wind, reflecting that it is best to be lowly, because for the "lowest and most dejected thing of fortune" (4.1.3) things can only get better. Then, he sees an Old Man leading the blinded Gloucester, who keeps asking him to leave him to die: "I have no way and therefore want no eyes./ I stumbled when I saw" (19-20). Gloucester laments his misjudgment of Edgar and says how much he wants to meet his son once more: "Might I but live to see thee in my touch/ I'd say I had eyes again" (24-5). As the Old Man catches sight of Edgar, Edgar notes his foolishness for thinking of himself as 'the lowest' before: "O gods, who is't who can say 'I am at the worst'?/ I am worse than e'er I was" (27-8).
Edgar's realization, upon seeing his blinded father, that it is impossible to know when you are at the worst, because things can always get even worse, suggest that there is no limit to the potential of unjust power to produce destruction and suffering. Gloucester, meanwhile, in the face of his own errors and the awful brutality of the world, has given up on living except for a desire to meet his true son once more.
The Old Man tells Gloucester that they had found Poor Tom. Gloucester notes that the previous night he saw such a mad beggar who "made [him] think man a worm" (37). He has learned, he says, about human lowliness: "As flies to wanton boys are we to the gods;/ They kill us for their sport" (41-2). He still does not recognize that the "naked fellow" (46) is his son. Sending the Old Man who was leading him back to fetch some clothing for "Poor Tom" (who is naked), Gloucester offers Poor Tom all the money in his purse to take him to the cliffs at Dover (where he intends to commit suicide).
Gloucester, when he first saw Poor Tom, thought him to be as low as a worm. But now Gloucester realizes that all men are like worms in the eyes of the gods – mere playthings, to be killed for fun. In the face of the terrible things he has done and seen, Gloucester despairs and wants only to cease to exist.