What was meant by vulgarizing in the Italian Renaissance?

What did it mean to “vulgarize” in Renaissance Italy? Was it simply a matter of translating into the vernacular, or did it mean making a text more accessible to the people – to in some sense popularize it? The answer is far from simple and certainly never one-sided; therefore, each individual case needs to be independently assessed on its own merits. This article seeks to shed some light at least on the major treatments of the theory of vulgarization by the likes of Ludovico Castelvetro, Faustus Longianus, Francesco Robortello, Alessandro Piccolomini, Orazio Toscanella and Girolamo Catena, which were central to the debate from the 1540s onwards.