Suppose, for the sake of easy memory, that the Middle Ages begin in A. D. 313, finish in 1313. The first date is marked by Constantine's Edict of Milan, virtually establishing Christianity as the religion of the Roman world empire. The second date emphasises the sudden death of Emperor Henry VII at Buonconvento in Tuscany during his Italian campaign, as the irreparable failure of the last attempt that could be undertaken, with a reasonable chance of success, to enact the plan of Roman-Christian unity under whose spell the Latin West and the Germanic North had dreamed and laboured all through those thousand years. Of this phase of history Dante is the witness and an actor, a victim and the judge as well.