" The degradation and impoverishment of the Jews in Europe, the fact that their contribution to the economy and culture had become marginal by the end of the Middle Ages, might have been expected to erode if not demolish the wall of hatred which had been built around them. But that did not happen. Like other forms of irrational conduct, anti-semitism did not respond to the laws of economics. On the contrary: like some vicious organism, it bred new mutations of itself. In Germany in particular it began to develop its own repulsive iconography–the Judensau. "

― Paul Johnson , A History of the Jews