What sins does Ruskin single out in the story, The King of the Golden River?

Ruskin singles out the sin of avarice, or greed for money, as the root of the evil in the Black brothers' characters. All of their cruelty and exploitation of others— their abuse of Gluck, their refusal to share anything they own with anyone else, their cheating, lying, and stealing— stems from their insatiable love of money. Their own obsession with gold drives them to their inevitable destruction.