Commentary Purg XVIII 118-120

San Zeno, just outside the city of Verona (and, by common consent, one of the most beautiful churches in Italy), was also the site of a monastery.  Its nameless abbot, who speaks here, is generally identified, as he is by Toynbee (Zeno, San), as 'Gherardo II, who was abbot, in the time of the Emperor Frederick I, from 1163 till his death in 1187.'  Frederick Barbarossa, emperor from 1152 until his death in 1190 as Frederick I, was a grandfather of Frederick II (emperor 1215-1250).  Dante's overall opinion of him is difficult to measure, since he so rarely refers to him, but in the two passages that do invoke him, here and in an Epistle (Epist.VI.20), his destruction of Milan in 1162 for its anti-imperial activities is clearly applauded.  On the question of Dante's views of Barbarossa see Nardi (Nard.1966.1).

      For the less than likely possibility that the adjective 'buon' (good) that precedes his name is here to be taken ironically, see Tommaseo (DDP Tommaseo.Purg.XVIII.118-120) on this passage.  One may add that the thirty occasions in the Commedia on which a reader finds the epithet combined with a name or title (e.g., 'buon Marzucco,' 'buon maestro') do not reveal a single one in which an ironic reading seems warranted.