As Sancho and Don Quixote ride further into the mountains, the knight reveals his plans. Sancho must go to Toboso and deliver a letter to the Lady Dulcinea. In the meantime, Don Quixote will do penance in the wilderness, after the manner of knights-errant who have been too-long absent from their mistresses. He describes to Sancho how he will express his madness and despair: "Thou wilt see me throw away my armor, tear my clothes, knock my head against the rocks, and do a thousand other things of that kind which will fill thee with astonishment." His squire begs that he be less harsh with himself, but the Don is adamant. Writing the letter, Don Quixote confesses that he hardly knows Dulcinea. Sancho is surprised that his master's ideal mistress is none other than the daughter of Lorenzo Corchuleo, a neighbor of his. He chatters about the wench's virtues and her peasant habits, and Don Quixote stops him by relating a short parable. "It does not matter what her background is," the knight concludes. "Dulcinea del Toboso, as to the use I make of her, is equal to the greatest princess in the world." He continues by saying that none of the ladies whose praises resound in ballads, novels, poems, or prayers have ever been made of flesh and blood "The greatest part of them were nothing but the mere imaginations of the poets for a groundwork to exercise their wits upon." Sancho, with tears at the parting, prepares to commence his journey.
Don Quixote explains to Sancho the real identity of his peerless mistress, informing the ignorant squire that the sublimity of a ladylove has little to do with her actual person. At the same time, the madman reveals the consciousness of Alonso Quixano, who bore a twelve-year-long love for a pretty peasant lass whom he saw on only four occasions. This unsatisfactory love may well have caused the hero to satisfy his romantic notions through books of chivalry. With his head full of "disordered notions," it follows that the hidalgo's humble and frustrated quest for immortality through fathering Aldonza Lorenzo's children can be sublimated into a knight's search for glory in the name of Dulcinea. Cervantes thus draws a relationship between the buried spirit of Alonso Quixano the Good and the militant Don Quixote; between the knight's knowledge of real identities and the idealizations he consciously forms; between, finally, the madness of the inspired knight and the feigned madness of the disappointed lover.
Just as religious fanatics strive to purify their souls of sinfulness by undergoing severe hardships, so may Don Quixote undergo penance to refine the common soul of Alonso Quixano. Another reason for the madness in the wilderness is Don Quixote's desire to prepare himself, like the fasting knights of old, for further adventures. Cervantes, in fact, has finished with the hero's burlesque adventures proving his character, and after this breathing spell the pattern of the knight's encounters changes. The hero is set in the role of laughingstock, not merely to the author, but to the world at large, and it is this theme that dominates in the second part of the history of the Manchegan knight.
At the same time that he provides hints of Don Quixote's deeper nature, Cervantes also develops the relationship between master and squire. More than ever do they depend on each other, and they weep at the separation. Not only is the penance a period of loneliness for the hero, but he misses Sancho's office of securing food and gets quite thin from poor nourishment. On the other hand, Sancho has so much relied on his master's intellect that he is more foolish than ever when alone. Completely forgetting to carry with him the carefully written letter and the order for three ass-colts absences symbolic of the literary Don himself Sancho is so helpless that the curate and the barber take advantage of him to play a trick on Don Quixote in order to bring him home for a rest cure.