De vulgari eloquentia, an essay by Dante Alighieri on the relationship between Latin and vernacular
Vidal also took pains to argue for the superiority of lemosà (or Lemozi, i.e., Occitan) over other vernaculars, prompting the Florentine poet Dante Alighieri to write a De Vulgari Eloquentia justifying the use of the Tuscan vernacular as opposed to the Occitan.