Don Quixote Volume 1, Chapter 45
The wronged barber, secure in the knowledge that he is in the right, asks those assembled around him if they believe his basin to be a basin. The barber from La Mancha, who wants to extend the fun, admits that he too is a barber, but has also been a soldier and as far as he is concerned it is a helmet although not a complete helmet. Cardenio and Don Fernando agree. (The judge is preoccupied with his own affairs and does not speak.) The wronged barber is flabbergasted. He tells them that if the basin is a helmet, then the saddlebag must be a fancy harness.
Don Quijote, who only cares about his helmet, says he thinks it's a saddlebag but he is not going to meddle. The priest insists that Don Quijote is the expert on these and all knightly matters and he must decide. Don Quijote cops out by saying he cannot reach a clear decision due to the enchanted nature of the castle that alters the appearance of objects to him. Those, in on the joke, decide to take a vote; those not in on it, are utterly confused by these proceedings. The vote is in, and Don Fernando speaks to the wronged barber:
"[S]o you'll simply have to resign yourself -- you, and your ass, too -- to the sad fact that this is indeed a decorative harness and not a saddlebag, and your case has been singularly badly argued and substantiated." Volume 1, Chapter 45, pg. 311
The wronged barber says they are all mistaken and so do one of the servants and a policeman. Don Quijote attacks the policeman and a riot breaks out as everyone starts fighting.
Don Quijote, taking on an uncharacteristic role -- as the voice of reason (although it is short-lived) -- shouts for everyone to stop before they all get killed. He explains that the castle is enchanted and infested with demons and that they have all been cast under a spell forcing them to reenact an argument from another time and place.
The policemen back down quickly when they learn they have been fighting aristocrats and nobles; but one officer studies his warrants and recognizes Don Quijote in the description of a man wanted for arrest for freeing criminals. He grabs Don Quijote by the collar and orders his arrest and Don Quijote promptly tries to strangle him; the innkeeper (also a deputy sheriff) comes to the aid of the policeman and his wife starts to shriek from seeing him in a fight for the third time today. Sancho remarks that the place must be enchanted because it's impossible to get any peace there!
Don Quijote and the officer are separated. Don Quijote, arrogantly laughing in their faces, explains that they are lowborn, putrid garbage and have no business trying to arrest him because he, Don Quijote, is outside and above the law; he is a law unto himself because he is a knight errant:
"[K]nights errant are exempt from the application of all laws and statutes, that for them law is their sword, statutes are their spirit, and edicts and proclamations are their will and desire." Volume 1, Chapter 45, pg. 314