A natural language […] is seen as an integrated part of the communicative competence of NLU [natural language user].
- Dik (1989), a pag.3

A natural language is an instrument of social interaction. That it is an instrument means that it does not exist in and by itself as an arbitrary structure of some kind, but that it exists by virtue of being used for certain purposes. These purposes concern the social interaction between human beings.
- Dik (1989), a pag.4

After all, natural language is a species-specific phenomenon. Such genetic factors, however, will be regarded as a last resort, to fall back upon when all other attempts at explaining the linguistic facts have failed.
- Dik (1989), a pag.7