Comparative religion has always been bedevilled by medical materialism. Some argue that even the most exotic of ancient rites have a sound hygienic basis. Others, though agreeing that primitive ritual has hygiene for its object, take the opposite view of its soundness. For them a great gulf divides our sound ideas of hygiene from the primitive's erroneous fancies. But both these medical approaches to ritual are fruitless because of a failure to confront our own ideas of hygiene and dirt.