In order to be used as a single unit, the enormous sum integrated by a concept
has to be given the form of a single, specific, perceptual concrete, which
will differentiate it from all other concretes and from all other concepts.
This is the function performed by language. Language is a code of
visual-auditory symbols that serves the psycho-epistemological function of
converting concepts into the mental equivalent of concretes. Language is the
exclusive domain and tool of concepts. Every word we use (with the exception of
proper names) is a symbol that denotes a concept, i.e., that stands for an
unlimited number of concretes of a certain kind.
(Proper names are used in order to identify and include particular entities in
a conceptual method of cognition. Observe that even proper names, in advanced
civilizations, follow the definitional principles of genus and differentia:
e.g., John Smith, with “Smith” serving as genus and “John” as
differentia—or New York, U.S.A.)