 The last two subdivisions found in Boethius are ‘of one origin’ (ab uno), with the example of the word ‘medical’, and ‘in relation to one’ (ad unum), with the example of the word ‘healthy’. These subdivisions correspond to Aristotle’s pros hen equivocation. The example ‘healthy’ (sanum) as said of animals, their diet, and their urine is particularly important here. ‘Sanum’, like other adjectives, was classified as a concrete accidental term. As such, it did not fall within an Aristotelian category, since its primary signification had two elements whose combination was variously explained. On the one hand, some kind of reference is made to the abstract entity health, which belongs to the category of quality; on the other hand, some kind of reference is made to an external object which belongs to the category of substance. This dual reference precludes the term from picking out a natural kind, though in the case of other adjectives, such as ‘brown’, no problem is caused thereby. Brown things may not form a natural kind, but at least they are all physical objects, and ‘brown’ is used in the same sense of each one. ‘Healthy’, however, is more complicated. To say that Rover is healthy is to say that Rover is a thing having health, and obviously this analysis can’t be applied to diet, which is called healthy only because it causes health in an animal, or to urine, which is called healthy only when it is the sign of health in an animal. Whatever the properties which characterize urine and food, they are different from those characterizing the animal.