Almost everyone swears, or worries about not swearing, from the two year-old who has just discovered the power of potty mouth to the grandma who wonders why every other word she hears is obscene. Whether they express anger or exhilaration, are meant to insult or to commend, swear words perform a crucial role in language. But swearing is also a uniquely well-suited lens through which to look at history, offering a fascinating record of what people...