One of the most widely read books in the social sciences, Purity and Danger established Mary Douglas as one of the twentieth century's leading social scientists. Her career spanned fieldwork in the Congo to wartime service in the British government to teaching at Oxford and Princeton, and her work continues to influence not only the social sciences but also fields as diverse as economics, design, and environmental studies. Douglas wrote 19 books, but it is on Purity and Danger, her study of how concepts of purity and dirt unite religions and societies, that her scholarly reputation chiefly rests. What we consider dirt, she says, tells us a great deal about how we create order in the world.