Lawrence, is about the responsibility of greed. The more money they get, the more they need it. But they need it and yet they want more of it to satisfy their own needs. But with greed everything comes with a price.
The family was very low on money, and yet they lived in a decent house with servants, just so they can keep up with the social status of the neighborhood. Paul's mother seems to be the head of the house, since mostly throughout the father is gone, but it looks like she takes care of the kids. She was always in debt and blamed their poverty on the father for the unluckiness, as it's demonstrated like this: ".she said slowly and bitterly, "it's because your father has no luck"". Paul is told, ".If you"re lucky you have money. That's why it's better to be born lucky than rich. If you"re rich, you may lose your money. But if you"re lucky, you will always get more money." When she received a letter from a lawyer, which was Paul's winnings from the race tracks five-thousand pounds in increments of a thousand pounds a year for her birthday, she immediately went to the lawyer asking for the full amount evidenced here: ".Paul's mother had had a long interview with the lawyer, asking if the whole five thousand could not be advanced at once, as she was in debt." After the meeting with the lawyer she got the whole sum, it is later known that the money was used on new furnishings, and a tutor for Paul. It's shown that the mother is greedy when she gets money, but even with a cold heart she still had a soft spot for Paul and cared for him when he fell on the floor, "Then he fell with a crash to the ground, and she, all her tormented motherhood flooding upon her, rushed to gather him up." Towards the end, when Paul died she gets the last of his winnings and never remembered that he was lucky.
Oscar Cresswell, the uncle of Paul, came by one day to visit. His spark of greed came alive at the moment Paul said his horse's name, the rocking horse he got for Christmas, was Sansovino, the name of the winning horse in the Ascot.