Langue is proposed by Saussure. It refers to the abstract linguistic system shared by all the members of a speech community. Langue is the social, conventional side of language, and it is the code. Langue is the abstract knowledge necessary for speaking, listening, writing and reading. It is relatively stable and systematic. Competence is proposed by Chomsky. According to Chomsky, competence refers to the knowledge that native speakers have of their language as a system of abstract formal relations. Chomsky’s distinction apparently corresponds in some degree to that of Saussure. It represents a similar classification of knowledge and behavior and a similar dichotomy of the scope of linguistic inquiry. However, their views are not exactly the same. Chomsky’s competence is a psychological construct and Saussure’s langue is a set of social conventions. Linguistic potential actually refers to a lot of possibilities to choose from, and it seems also defined from the perspective of psychology. Whether we adopt a psychological view or a sociological one, the principle is to abstract rules from immediately observable language use and try to describe the system governing particular examples of speaking or writing.