 The basic idea of the standard medieval realist theories of meaning was that semantic classifications derive from ontological differences among the signified objects. So, according to this approach, the simple expressions of our language (i.e., names) are distinct from the complex expressions (i.e., sentences) by virtue of their own significata, that is by virtue of the different kinds of objects they make known. In fact, the objects signified by complex expressions are compounds of (at least) two of the objects signified by simple expressions and a relation of identity (or non-identity, in the case of a true negative sentence), while a simple object is an item in a category (i.e., either a singular substance, or a substantial form, or an accidental form). Furthermore, every simple expression of our language is like a label naming just one object in the world, but whereas proper names and singular expressions label individuals (i.e., token-objects), general terms label common natures (i.e., type-objects), which are the main metaphysical constituents of the set of individuals instantiating them. For instance, the general expression ‘man’ labels and can stand for each and every man only because of its primarily signifying the universal form of humanity qua being present in each and every man as the main constitutive principle of his essence.