 Entities also play a role as semantic values of quantificational NPs, more precisely, the variables that serve to formalize them. Ontological commitment has been tied to the role of semantic values of variables by Quine (1948), who put forward the dictum “to be is to be the value of a variable”. This was meant to apply not so much to natural language, though, but to regimentations of it in formal theories of science. Yet being the semantic value of a variable or being in the domain of a quantificational NP has become a well-established criterion for being an entity in the practice of natural language ontology.