Don Quixote Volume 2, Chapter 6
Meanwhile, the housekeeper and niece could tell that Don Quijote is intending to go off as a knight errant again. His niece asks him why couldn't he be a knight at court instead. He explains to that knight errants are in a class all their own and gives her a short synopsis of their great and mighty deeds that illustrate their courageous hearts. The niece tells him that these stories are just nonsense and that they aren't true! Angered, he invalidates her and her right to even dare to have an opinion on such a matter -- she, who is "barely able to waggle a dozen lace bobbins"! (pg. 390) His niece asks how is it possible for him to be so wise and insightful on some matters and yet completely deluded on others:
"[Y]ou think you're brave and courageous, when you're really old; you think you're strong, when you're really feeble; you think you can go righting wrongs when age has bent you in half -- and, above all, that you're a knight, when you're not, because even though gentlemen can become knights, poor ones can't!" Volume 2, Chapter 6, pg. 390
Nicely sidestepping most of his listed delusions, he zeroes in on the issue of his being a poor gentleman. He proceeds to outline the various types of family trees and summarizes his thesis that in the end all families are connected. Out of patience, his niece agrees sarcastically that her uncle knows all and can do all! And that he could build a house as easily as a bird cage if he set his mind to it. Don Quijote agrees; that there is nothing he cannot do if he sets his mind to it and that he could make bird cages and toothpicks very well if he wanted to. Sancho arrives and he and his master go off to speak in private.