The traditional focuses of sociology include social stratification, social class, social mobility, religion, secularization, law, sexuality and deviance.
These were called calceus mulleus, and the name may have been shortened to mules by English speakers. Hence the primary difference between mules and clogs in early days was that clogs were likely to be worn by working people, and mules were fancier and favored by the aristocracy.
Mule(noun) a hybrid animal; specifically, one generated between an ass and a mare, sometimes a horse and a she-ass. See Hinny. Mule(noun) a plant or vegetable produced by impregnating the pistil of one species with the pollen or fecundating dust of another; -- called also hybrid. Mule(noun) a very stubborn person.