Although not his most famous work, one of Dante Alighieri’s most important ones was a composition entitled De Vulgari Eloquentia (On Eloquence in the Vernacular or Concerning Vernacular Eloquence), in which the author discusses the development of the Romance languages. He divides Europe into three portions: to the north, the Germanic languages; to the east, the Greek-based languages, and to the south, the Romance languages. Dante further subdivides the southern languages into three branches – the language of Oc (Occitan), the language of Oïl (now contemporary French), and the language of Sì (Spanish, Italian, and Portuguese). The emblem for these groups is the word “yes.”
In southern France, Monaco, and parts of Italy and Spain, oc was used traditionally for “yes”, whereas in northern France and parts of Belgium, oïl was used. Sì was used in most of Spain, Portugal, and Italy. All three words come from Latin terms of agreement: oc originated in hoc, meaning “this,” oïl from hoc illud, meaning “this is it,” and sì from sic, meaning “thus it is.” While oc and oïl are rarely used in contemporary languages, the sì form is still utilized in Spanish, Italian, and Portuguese (sim).
The Occitan language declined in usage and popularity beginning in the 14th century, around the time that French royal power – seated in northern France – extended its domain over the rest of the country. Eventually, in 1539, the langue d’oïl became the official language of French administration by a piece of legislature known as the Ordinance of Villers-Cotterêts. This document, signed by King Francis I in the northern city of Villers-Cotterêts, was the second-to-last blow for the Occitan language. The final one was the French Revolution, whose proponents emphasized unity of language, and so encouraged the use of a single French dialect. The Occitan language enjoyed a minor resurgence after World War I, in part due to the spread of Occitan speakers in France and in part due to the emergence of poets, playwrights, and authors from southern France who emphasized their cultural heritage and language.