Those whose attitude toward material goods deviated from the appropriate mean are punished in the fourth circle. They include the avaricious or miserly (including many "clergymen, and popes and cardinals"), who hoarded possessions, and the prodigal, who squandered them. The two groups are guarded by a figure Dante names as Pluto, either Pluto the classical ruler of the underworld or Plutus the Greek god of wealth (who uses the cryptic phrase Papé Satàn, papé Satàn aleppe), but Virgil protects Dante from him. The two groups joust, using as weapons great weights which they push with their chests: … I saw multitudes to every side of me; their howls were loud while, wheeling weights, they used their chests to push. They struck against each other; at that point, each turned around and, wheeling back those weights, cried out: Why do you hoard? Why do you squander? The contrast between these two groups leads Virgil to discourse on the nature of Fortune, who raises nations to greatness, and later plunges them into poverty, as she shifts "those empty goods from nation unto nation, clan to clan." This speech fills what would otherwise be a gap in the poem, since both groups are so absorbed in their activity that Virgil tells Dante that it would be pointless to try to speak to them – indeed, they have lost their individuality, and been rendered "unrecognizable"
Taken from Dante's Inferno on Wikipedia