This chapter addresses the motivation for the emergence of classifiers. Before Middle Chinese, there was no such category as “classifier” in the grammar of the Chinese language, and this word “classifier” was historically innovated. Individual classifiers started to emerge as early as Late Old Chinese, and the number of classifiers steadily increased over time. However, the rigorous grammatical rule that required a proper classifier for every numeral phrase was firmly established around the fourteenth century AD. Importantly, there was a parallel development of nominal and verbal classifiers; that is, verbal classifiers came into existence not long after the emergence of nominal classifiers.

This chapter discusses phonological motivations for morpho-syntactic changes in history. In general, Old Chinese was monosyllabic, which means that the overwhelming majority of words were represented by a single syllable, regardless of whether they were content or function words. In Middle Chinese, the phonological system was dramatically simplified; the number of consonants and vowels was reduced, and the syllabic structures were simplified. To restore the phonological distinctions of lexical items, the language increased the number of syllables for words, typically by adding one syllable to originally monosyllabic words. This disyllabification tendency has lasted nearly two millennia since then. This new sort of prosodic unit stimulated the fusion of two monosyllabic items, a key factor for the emergence of the resultative construction and other grammatical morphemes.