The Stone Operation.
An old Dutch saying to describe a person who behaved oddly or eccentrically was that 'he had a stone in the head'. Taking advantage of the credulity of simple people, charlatans would offer to extract these "head stones." They would always find patients among sufferers of regular headaches or migraines. The 'surgeon' would then tie the patient safely to a bench, make a small cut and, accompanied by the cries, moans and groans of the victim produce a pebble or two covered with blood. These 'surgeons' were a popular object of satire in the 17th century