Commentary Purg VII 16-18

Virgil, apostrophized by Sordello both as foremost among all Latin poets and as his greatest townsman, is here cast as the founder of all Romance poetry.  The precise meaning of lingua nostra (our language) has been debated (see Mazzoni's summary of the debate [Mazz.1977.2], p. 164), and includes a wide range of possibilities: all human vernacular; Latin alone; all poetry, vernacular and Latin; and vernacular that is specifically developed from Latin.  This last seems the most acceptable reading, making Latin the 'mother tongue' of the Romance vernacular poets, as would also seem to be the case at [Purg XXI 94-99].