  (The inclusion is strict because of the ‘equipollence’ constraint.) In other words, genuine universals are arranged in a hierarchy: given two universals, either they are related as genus and species, all instances of one being instances of the other, or else they are completely disjoint, having no instance in common (e.g. cowhood-animalhood, cowhood-treehood). The Nyāya say that, if one universal is thus subsumed by another, the former is ‘lower’ (apara) and the latter is ‘higher’ (para) (cf. TS 6). The ‘highest’ universal of all is ‘existentness’ (sattā), into whose extension falls every substance, quality and motion. The demand that universals be organised hierarchically shows that the Nyāya took as their paradigm the biological species, which tend to exhibit this structure. Bearing in mind that the term for “universal”, i.e. “jāti” is also the word for caste, Matilal (1971: 76) speculates that