 During the same period in which Dante was writing the Convivio he was also composing the De vulgari eloquentia. Written in Latin, this treatise was, like the Convivio, abandoned sometime around 1307. In it, however, many of the lengthy discussions of ethics and politics from book 4 of Convivio are put in the service of a discussion of the capacity of poets possessing both scientia et ingenium—that is, those who possess both knowledge and genius [DVE 2.1.8]—to use an illustrious vernacular language to “melt the hearts of human beings, so as to make the unwilling willing and the willing unwilling” [1.17.4]. Underwriting this purpose, Dante offers a wholly unique treatment of the origins and development of language in book 1 before proceeding in book 2 to set down specific rules that ought to govern the proper poetic deployment of this illustrious vernacular.