This is a meta-level predicate for distinguishing very general classes, which in the analytic philosophy literature are taken to be 'uncountable' (cf. Griffin, 1977: a part of something belonging to the class c belongs to c as well;
in other terms, an instance of a category class is internally homogeneous). A problem is that such a description is applicable to 'mass' objects (a piece of gold, an amount of water, etc.) as well, which are not exactly very general in the common intuition. Cognitive semantics provides us a criterion for further intuition: a category class is (cognitively) reidentifiable by means of a single image-schema (container, path, etc., cf. Mark Johnson, 1989), while masses are reidentified on the basis of material properties. Another way for distinguishing masses from categories at meta-level is granularity (see theory: layers): a mass has homogeneous parts as far as the same granularity (or an adjacent one) is maintained: for example, a part of a piece of gold is gold until the atomic granularity, but not at sub-atomic granularity; a part of a food is the same food till molar granularity, but not at molecular granularity, etc.
(Inherited-Slot-Value Category The-Archetype Category)
(=> (Category ?Self)
(Forall (?Homog ?X ?Y)
(=> (And (Isa ?Homog Entity)
(Instance-Of ?X ?Self)
(Instance-Of ?Y ?Homog)
(Part-Of ?Y ?X))
(Identity ?Self ?Homog))))