Sancho tells Quixote triumphantly that enchanted people don’t have that need, and therefore he must not be enchanted. But Quixote explains again that times have changed, and enchanted people do all sorts of things they didn’t before – “the customs of the times” do not prove anything when it comes to enchantment. Sancho does not try to argue, but insists that they must try to get Quixote out of the cage. He asks the priest to let Quixote out so that he can relieve himself. Quixote explains that there’s no chance of him fleeing, since he is enchanted, so the priest lets him out.
Now Quixote has become more sure of his theory about enchantment, chivalry, and knight-errantry. These three things are not particular to any place and time – they can reincarnate anywhere, in any era. In light of this realization, Quixote’s project of resuscitating knight-errantry seems very reasonable.
After he returns, the canon asks him how it can be that such an intelligent man believes all the lies in chivalry books. He encourages Quixote to read all the wonderful truthful books instead, like history books and the Bible. Quixote answers that it is folly to say that knights errant never existed, when so many people believe their stories to be true; they are as true as the sun is bright, ice is cold, and the earth is sustaining. Quixote gives examples of both real and fictional events to prove his point.
When the guests at the inn all looked at a barber’s basin and called it a helmet, the basin, to some mysterious degree, transformed into a helmet. Similarly, when thousands of people imagine the stories in chivalry books and believe them to be true, the stories acquire the quality of truth. They are true because they are bright in people’s imaginations. For Quixote, anything that sustains us is true.