Style has been part of rhetoric since the days of the Sophists, when speakers such as Gorgias held audiences spellbound with their flourishes. Throughout history, however, characterizations of style were highly subjective, with good reason: Discussions of style relied on metaphor. The development of new rhetoric changed matters considerably because of the link to linguistics. Although transformational-generative grammar has its share of metaphors, the phrase-structure grammar it uses as a foundation is empirical and associated with word counts, sentence length, and so forth. Linguistics gave scholars in the 1960s tools with which they could reevaluate style, which quickly came to be viewed as the linguistic choices a writer makes in the course of producing a text.
Differences between speech and writing were of special interest during this period because literacy was deemed a reflection of cognitive development. In this case, not only writing but also stylistic maturity was seen as a manifestation of reasoning ability. The presumed connection between language and mind formed part of the rationale for several studies in the mid-1960s that attempted to identify the characteristics of sentence or syntactic maturity. Hunt ( 1965) pioneered this work, determining that as writers mature they produce sentences with longer clauses.
On the basis of such research, theorists proposed that syntactic maturity could be increased through direct instruction. The result came to be widely known as sentence combining, which consists of exercises that require students to manipulate combinations of sentences, a technique that helps develop syntactic fluency. Although the popularity of sentence combining has declined considerably over the last decade, it was an important movement in new rhetoric and had a major effect on writing instruction. Whenever teachers attend to style today, they usually introduce students to sentence combining.