"A language is a dialect with an army and navy" is a description of the distinction between dialect

Dialect

The term dialect is used in two distinct ways, even by linguists. One usage refers to a variety of a language that is a characteristic of a particular group of the language's speakers. The term is applied most often to regional speech patterns, but a dialect may also be defined by other factors,...

 and language

Language

Language may refer either to the specifically human capacity for acquiring and using complex systems of communication, or to a specific instance of such a system of complex communication...

. It points out the influence that political conditions can have over a community's perception of the status of a language or dialect. The description was popularized by the Yiddish linguist Max Weinreich

Max Weinreich

Max Weinreich was a linguist, specializing in the Yiddish language, and the father of the linguist Uriel Weinreich, who edited the Modern Yiddish-English English-Yiddish Dictionary.- Biography :Max Weinreich began his studies in a German school in Kuldiga,...

, who heard it from a member of the audience at one of his lectures.
This statement is commonly attributed to one of the leading figures in modern Yiddish linguistics, Max Weinreich, who expressed it in Yiddish:


(a shprakh iz a dialekt mit an armey un flot).