The distributive concept of class, secured in the theory of sets against the antinomies connected with its pre-theoretical stage, plays a very important role in the language of modern science. It turned out to be an irreplaceable tool for the formulation of theorems of different branches of mathematics and made possible the development of many new theoretical constructions or even whole new disciplines of great scientific importance. This concept has also applications in the philosophy of language, especially in the so-called theory of referential meaning of expressions, which describes the relation between language and what language can refer to.