grammar has focused on the following familiar

Morphemes are then arranged grammatically into such higher level units as words: bites, biting, quickly (some morphemes are of course already words: dog, bite,man,quicJ()\then phrases of various sorts, e.g. the dog (which can function, among other ways, as a "subject"); then clauses of various sorts (in English, such constructions contain a subject and predi­cate); and finally sentences, which are marked in some way as not being parts of still larger constructions.

Recent interest in grammar has focused on the following familiar and yet astonishing (and somehow disturbing) fact—any speaker can say, and any hearer can understand, an infinite number of sentences; and, indeed, many of the sentences we say and hear have never been said before.