[...] language consists of two layers of habit. One layer is phonemic: the speakers have certain habits of voicing, tongue-movement, and so on. These 'habits' make up the phonetic system of the language. The other layer consists of formal-semantic 'habits': the speakers habitually utter certain combinations of phonemes in response to certain types of stimuli, and respond appropriately when they hear the same combinations. These habits make up the grammar and lexicon of the language. (pp.364-365)
- Bloomfield (1935), a pag.364-365