Commentary Inf XXVIII 103-108

The description of Mosca dei Lamberti is one of the most affecting in this canto filled with affective moments. Mosca was among those Florentine citizens mentioned by Dante ([Inf VI 80]) as having attempted to do good in the divided city; for his crime, of those mentioned he is the farthest down in hell. A fervent Ghibelline, in 1216 he urged the murder of Buondelmonte dei Buondelmonti, who, engaged to a girl of the Amidei family, married a Donati instead. The result of this killing was the origin of the bitter rivalry between the Amidei and the Donati, Ghibellines and Guelphs respectively, and of the civil discord that tore Florence apart. Mosca is thus seen as a modern-day Curio, urging the powerful to do what in their hearts they must have known was not to be done.

His words, 'a done deed finds its purpose,' so mercilessly laconic, now cause him enough by way of regret that we can sense some justification in Dante's original characterization of him.