No one kills Don Quixote: he falls ill at home, regains his wits, and dies in bed, in chapter LXXIV of Part Two, as Alonso Quijano the Good. The narrator says the fever came either from the melancholy caused by seeing himself defeated or from the disposition of heaven, and the doctor concludes that melancholy and vexations are finishing him off.
Defeat is the antechamber. On the beach at Barcelona, the Knight of the White Moon knocks him down and imposes a year of retirement without arms; it was the bachelor Sansón Carrasco, who had staged the duel to cure him. Back in the village, the gentleman takes to his bed, and after sleeping more than six hours he wakes up saying that his mind is free and clear, that he now knows the absurdities of the books of chivalry, and that he only regrets that the disillusionment came so late.
He asks for confession and a will, wants death not to confirm his reputation as a madman, and announces to his friends that he is no longer Don Quixote de la Mancha but Alonso Quijano, whom custom has given the reputation of Good, and that he is an enemy of Amadis of Gaul. Sancho, weeping, begs him to live and go to the countryside dressed as a shepherd; the gentleman replies that in the nests of yesteryear there are no longer the birds of today. He leaves bequests, asks forgiveness of Sancho and of the author of the false book, and dies after receiving the sacraments.
The notary says he never read in a book of chivalry that a knight-errant had died in bed so peacefully and so Christianly. The priest asks for a certificate of natural death so that no other author, except Cide Hamete, may bring him back to life. For one reading, the book changes tone like a symphony, from irony to bitterness, until a most sorrowful ending; for Auerbach, there is no tragedy there to read.