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 oil with a metal scraper, and giving himself a final oiling - all done daily, in company and without soap.

Even more than in the eye or the nose, cleanliness exists in the mind of the beholder. Every culture defines it for itself, choosing what it sees as the perfect point between squalid and over-fastidious.