Lear, Kent and the Fool arrive at the hovel. Lear still insists that the "tempest in his mind" has taken "all feeling" from his senses beyond his anger and sadness at his daughter's ingratitude. As the Fool goes inside the hovel, Lear pauses to reflect that he has spent too little time thinking about his poor subjects who were regularly exposed to such hardships. If powerful people spent more time thinking about such matters, he decides, they would be more generous with what they have, making the heavens more just.
As his daughters' violation of their duties to him, and the physically punishing experience of natural chaos in the form of the storm, drive Lear to madness, his reduced (nearly animal) state gives him a moment of insight into the lives of those less privileged—which he implies he lacked when he was king.
The Fool darts back out, reporting that someone is in the hovel: a spirit named Poor Tom. Edgar emerges raving as if possessed by the "fiend," or devil, in his Bedlam beggar disguise. Lear comments over and over that Edgar could only have been brought to this lowly state by "unkind" or "pelican daughters" (3.4.77; 81). Then he goes on to observe that Edgar would be better off dead than exposing his "uncovered body" (109) to the storm and that he has reduced himself to the state of an animal (as Edgar said was his plan in 2.3): "unaccommodated man is no more than such a poor, bare, forked animal as thou art" (113-5).
In Lear's eyes, Edgar, a madnman wearing just the barest rags for clothes, offers a stark contrast to his unjust daughters, dressed in their furs and robes. This semi-animal, semi-human figure emerges from the natural chaos of the storm, and exists outside the usual social/legal order (remember, Edgar is fleeing justice: the price his own father has put upon his head).
Gloucester approaches with a torch. Failing to recognize the disguised and raving Edgar as his son, he leads Lear, Kent, Edgar, and the Fool to a house.
Gloucester's failure to recognize his own child, echoing Lear's failure to recognize his long-faithful servant Kent, provides a literal emphasis to Lear's metaphorical "blindness" to the true qualities of his daughters.