To modern Westerners life without showers is unimaginable, but mankind somehow survived before the advent of soap and deodorants. For the modern, middle-class North American, “clean” means that you shower and apply deodorant each and every day without fail. For the aristocratic 17th-century Frenchman, it meant that he changed his linen shirt daily and dabbled his hands in water, but never touched the rest of his body with water or soap. For the Roman in the first century, it involved two or more hours of splashing, soaking and steaming the body in water of various temperatures, raking off sweat and...