Commentary Par XVII 72

See Tozer (DDP Tozer.Par.XVII.71-72): 'The arms of the Scaligers were a golden ladder in a red field, surmounted by a black eagle, which was the imperial ensign.'  Unfortunately for Dante's sake, this insignia was not chosen by the Scaligeri (at the earliest, by Bartolommeo) before 1301.  By making it present now, in 1300, the poet hurries history along faster than it wants to go.