[...] a grammar has to be regarded as "a system of rules that expresses the correspondence between sound and meaning" [Chomsky, Noam, 1971, “Deep Structure, Surface Structure, and Semantic Interpretation”, STEINBERG & JAKOBOVITS (1971], p. 183] in a language. It does this by generating the sentences of this language so that each sentence is provided with a structural desciption and semantic representation. Such a grammar is thus regarded as a model of the linguistic competence of a speaker/hearer, who can produce and understand any number of sentences he has never heard before.
- Kastovsky (2004), Pag. 203

[...] the grammar as a whole defines the notion "possible sentence" for this language.
- Kastovsky (2004), Pag. 204