[571] _Michael Scott_: Of Balwearie in Scotland, familiar to English readers through the _Lay of the Last Minstrel_. He flourished in the course of the thirteenth century, and made contributions to the sciences, as they were then deemed, of astrology, alchemy, and physiognomy. He acted for some time as astrologer to the Emperor Frederick II., and the tradition of his accomplishments powerfully affected the Italian imagination for a century after his death. It was remembered that the terrible Frederick, after being warned by him to beware of Florence, had died at a place called Firenzuola; and more than one Italian city preserved with fear and trembling his dark sayings regarding their fate. Villani frequently quotes his prophecies; and Boccaccio speaks of him as a great necromancer who had been in Florence. A commentary of his on Aristotle was printed at Venice in 1496. The thinness of his flanks may refer to a belief that he could make himself invisible at will. [572] _Guido Bonatti_: Was a Florentine, a tiler by trade, and was living in 1282. When banished from his own city he took refuge at Forlì and became astrologer to Guido of Montefeltro (_Inf._ xxvii.), and was credited with helping his master to a great victory.--_Asdente_: A cobbler of Parma, whose prophecies were long renowned, lived in the twelfth century. He is given in the _Convito_ (iv. 16) as an instance that a man may be very notorious without being truly noble. [573] _Herb and image_: Part of the witch's stock in trade. All that was done to a waxen image of him was suffered by the witch's victim. [574] _Cain and the Thorns_: The moon. The belief that the spots in the moon are caused by Cain standing in it with a bundle of thorns is referred to at _Parad._ ii. 51. Although it is now the morning of the Saturday, the 'yesternight' refers to the night of Thursday, when Dante found some use of the moon in the Forest. The moon is now setting on the line dividing the hemisphere of Jerusalem, in which they are, from that of the Mount of Purgatory. According to Dante's scheme of the world, Purgatory is the true opposite of Jerusalem; and Seville is ninety degrees from Jerusalem. As it was full moon the night before last, and the moon is now setting, it is now fully an hour after sunrise. But, as has already been said, it is not possible to reconcile the astronomical indications thoroughly with one another.--Virgil serves as clock to Dante, for they can see nothing of the skies. CANTO XXI.