The Linguistics of Speech di William A. Kretzschmar Junior

There is an internal conflict in any language: the one between rule and use. The rule tends to preserve the structures, while the use to change them. The language is the product of this conflict. This differentiation, already well known to the Greek-Latin world, has found its modern codification in the reflection of Saussure (1916) who distinguished the system (Langue) from the product (Parole) and delimited the areas of competence of the science of the speech. Thus it is talked about the linguistics of Langue and the linguistics of Parole.