For generations, there has been no better illustration of the collective idiocy of the crowd than the story of the English calendar riots of 1752. At the trial of Henry Hunt and others for treason in 1820, James Scarlett, the prosecuting counsel, had this to say: 'The ridiculous folly of a mob had been exemplified in a most humorous manner by that eminent painter, Mr. Hogarth. It was found necessary many years ago, in order to prevent a confusion in the reckoning of time, to knock eleven days out of the calendar, and it was supposed by ignorant persons that the legislature had actually deprived them of eleven days of their existence. This ridiculous idea was finely exposed in Mr. Hogarth's picture, where the mob were painted throwing up the...