Don Quixote Volume 2, Chapter 29
They reach the banks of the River Ebro and Don Quijote spots a small boat without oars tied up and decides that it is an enchanted boat that has been placed there for him in order to help someone in trouble. He explains to Sancho that this is just how it happens in the books and tells him to tie up the animals. Sancho says he will obey but feels duty-bound to tell his master that the boat probably belongs to some fishermen as this river is know for its excellent shad. They head out in the boat and Sancho starts crying after he hears his donkey braying plaintively. Don Quijote calls him a coward and tells him to enjoy the ride as they are about to pass the equatorial line.
They head towards large water wheels of some flour mills which Don Quijote claims is the castle city in which lies the person who needs his help. The millworkers (with their flour-coated faces and white clothes) yell for them to stop before they get crushed by the wheels. Don Quijote knows an adversary when he sees one and responds by yelling at them to release their prisoner. Sancho is praying for deliverance. With poles, the millworkers manage to push the boat away from the wheels, but it turns over dumping out squire and madman, before going under the water wheels that smash it to little bits. The fishermen show up, take Sancho's clothes and demand payment for the boat. Don Quijote tells them he will gladly do so, but first they must release the prisoner to him. They call Don Quijote a lunatic, and he decides that this misfortune must be due to two powerful magicians at cross-purposes -- one sent a boat for him, the other dumped him in the water. He calls out his apologies to the captive, pays the fisherman and he and Sancho return to horse and donkey.