How do we know that all these works are Dante’s? it will be asked. Here we rest on unusually sure ground, for which once more we have to thank Villani. In the Chapter to which we have already more than once referred, containing the notice of Dante’s death, that historian gives a list of his works. “In his youth,” we read-- “he made the book called _The New Life of Love_; and afterwards, when he was in exile, he made some twenty moral and amatory odes, very excellent; and, among others, he wrote three notable letters, one to the Government of Florence, lamenting his own exile without any fault; the second he sent to the Emperor Henry; the third to the Italian cardinals, when the vacancy occurred after the death of Pope Clement.... And he made the _Comedy_, wherein, in polished rhyme, and with great and subtle questions of morals, nature, and astrology, philosophy and theology ... he composed and treated in one hundred chapters, or chants, concerning the being and condition of Hell, Purgatory, and Paradise.... He also made the _Monarchy_, in which he treated of the duty of the Pope and of the Emperor. And he began a commentary on fourteen of the above-mentioned moral odes, in the vulgar tongue, which, through his death supervening, is only completed for three.... Also he made a little work which he calls _De Vulgari Eloquentia_, whereof he promises to make four books, but only two are extant, perhaps by reason of his speedy end; in which, in powerful and elegant style, and with fine arguments, he examines all the vernaculars of Italy.” The last two paragraphs, it should be said, do not occur in all manuscripts. But, assuming them to be genuine, it will be seen that we have here an almost contemporary notice, with one or two exceptions, of all the main works now contained in the editions of Dante. The chief exception is the curious little treatise on physical geography, called _De aqua et terra_, which purports to be a lecture delivered by Dante at Verona, in the last year of his life; but this is of very questionable genuineness. It was first printed, indeed, in 1508, but no manuscript of it is now known to exist.