As Dante explains in book I of the Monarchia, it is necessary that human society and all earthly things be governed by the authority of a single Emperor.
All other political authority should be seen as deriving from that of the Emperor, who in turn derives his political authority from God.
Dante took politics very seriously, and his incorporation of so much political material into his journey through Hell serves the double purpose of situating his own political ideals in a larger moral scheme and warning his readers about the dangers of his enemies' political ideals.
Thus, Dante posits two ends for man: an earthly end and a heavenly end.
While the earthly end is centered on philosophy and the perfection of man's natural virtues, the heavenly end absorbs philosophy into the specifically Christian virtues of faith, hope and charity.