Historically, the Sardinians have always been quite a small population scattered across isolated cantons, sharing demographic patterns similar to the neighbouring Corsica; as a result, Sardinian developed a broad spectrum of dialects over the time. Starting from Francesco Cetti's description in the 18th century, Sardinian has been presented as a pluricentric language, being traditionally subdivided into two standardized varieties spoken by roughly half of the entire community: the dialects spoken in North-Central Sardinia, centered on the orthography known as Logudorese ("su sardu logudoresu"), and the dialects spoken in South-Central Sardinia, centered on another orthography called Campidanese ("su sardu campidanesu"). All the Sardinian dialects differ primarily in phonetics, which does not considerably hamper intelligibility; the view of there being a dialectal boundary rigidly separating the two varieties of High Sardinian has been in fact subjected to more recent research, which shows a fluid linguistic continuum from the northern to the southern ends of the island. The dualist perception of the Sardinian dialects, rather than pointing to an actual isogloss, is in fact the result of a psychological adherence to the way Sardinia was administratively subvidided into a "Caput Logudori" ("Cabu de Susu") and a "Caput Calaris" ("Cabu de Jossu") by the Spanish.