The language of the Roman Empire, spoken and written, was Latin. Like all languages spoken over a wide area for a long time, it varied greatly. Since the arrival of sociolinguistics in the 1960s, it has been accepted that such variation is in no way unnatural or sinister, and the flexibility it implies is often an advantage rather than a problem. But standardization of the Latin language was taken seriously, particularly within the traditions established by Aelius Donatus in the 4th century and Priscian in the 6th, with the result that eventually features of the language that did not accord with the precepts of these authorities were regarded as not just different but wrong. The concept of Vulgar Latin has been defined in a variety of different ways, but József Herman’s definition, as a label for all those features of Latin that we know existed, but which were not recommended by the grammarians, is probably the most useful; its meaning has thus usually been defined in opposition to that of another concept of dubious value, Classical Latin, the Latin of the grammarians (see grammar, grammarians, Latin).