Among the themes eNotes.com lists for D.H. Lawrence's "The Rocking-Horse Winner," the two that strike a chord with me are greed vs. generosity, and responsibility.
Paul, the young boy in the story, deeply feels his family's need for money. It is not only stressed by his mother, but the very house seems to whisper it to him. The child believes that by riding his rocking-horse, he will be able to predict what horse will win at the races. This plan actually works, but no matter how well he does, the need for money only grows until it drives Paul out of his mind—drives him to "ride" his horse to a state of collapse. As he lies dying, he learns that the horse he had picked has won the big race, and there is an enormous amount of money for the family. He tells his mother, ironically, how lucky he is—believing as his mother had said, that luck leads to financial success. Hester's brother (Uncle Oscar) is appalled at the situation. He says to his sister, whose "heart was a stone:"
...Hester, you're eighty-odd thousand to the good, and a poor devil of a son to the bad. But, poor devil...he's best gone out of a life where he rides his rocking-horse to find a winner.
In terms of parental responsibility, Paul's parents' job is to care for their children and allow them to be children, not to transfer worry and obsession over finances onto the children. Paul's mother and father are irresponsible, never truly dedicated parents, and obviously unsuccessful in finding a proper way (working and budgeting) to pay the bills. Instead of showering her son with love and providing him with a sense of well-being, Paul's mother explains their poor financial state by blaming it all on her husband's lack of luck! Paul is too young to have to shoulder such a heavy burden, but he does, and he starts riding to make money.
With regard to generosity vs. greed, Paul is the generous member of the family who turns over all of his profits to the family with the hope that it will improve the constant worry over money. However, Paul's careful planning is confounded by his greedy mother who takes the 5,000 he (secretly) makes available to her, and spends it all on things for the house, rather than investing it or saving it. It is Paul's generous nature that motivates him to earn more money when the first "installment" disappears so quickly and leaves the family no better off than they were before. This generosity is what ultimately pushes the boy beyond his physical, mental and emotional limits, and eventually robs him of his life.
What is Lawrence's most important message to his reader? For me, it is that family is more important than things. Parents are adults and need to act as such in order to take care of their children. Nothing else is of importance. By assuming responsibility to the family, bills will get paid and the family will thrive in an environment of love. More money can be made by working harder, but family is the most precious resource people can have, and it must be guarded and cared for as such for it is irreplaceable.