The theme of "The Rocking-Horse Winner" is stated in the New Testament:
For the love of money is the root of all evil: which while some coveted after, they have erred from the faith, and pierced themselves through with many sorrows.
1 Timothy 6, King James Version
If money was so important to people when Paul wrote those words in 62 A.D., when there was so little to buy with it, how much more important must it be to most of us nowadays when there is virtually no limit to the number of big and shiny things we can acquire? There is hardly a time when we are satisfied, although we may be almost satisfied, if only we had this or that gadget or knickknack. Most of us are a little bit like Paul riding that rocking-horse and getting nowhere.
Money is our madness, our vast collective madness.
D. H. Lawrence
In Chaucer's Canterbury Tales, the moral stated by Paul in 1 Timothy 6 is repeated many times in Latin by the Pardoner, who has an ulterior motive for doing so:
Radix malorum est Cupiditas
This is in the Prologue to "The Pardoner's Tale" in Chaucer.
My theme is alwey oon, and ever was—
“Radix malorum est Cupiditas.”
Paul's mother in D. H. Lawrence's story is obsessed with cupidity (defined as greed for money or possessions). She makes herself unhappy because she has no way of getting more money except through her husband, and she makes him unhappy because he is unable to satisfy her wants. She displays a common psychological reaction which has been called the Medea Complex. She loses her affection for her children when she loses her affection for her husband. She sees her husband in her children. And they, as Lawrence shows, are hypersensitive to their mother's real feelings. She is the root of all her family's unhappiness, and the root of her unhappiness is her cupidity.
She had bonny children, yet she felt they had been thrust upon her, and she could not love them. They looked at her coldly, as if they were finding fault with her. And hurriedly she felt she must cover up some fault in herself. Yet what it was that she must cover up she never knew. Nevertheless, when her children were present, she always felt the centre of her heart go hard. This troubled her, and in her manner she was all the more gentle and anxious for her children, as if she loved them very much. Only she herself knew that at the centre of her heart was a hard little place that could not feel love, no, not for anybody.
Everything in the story proceeds from Hester's love of money. She is a materialist. She doesn't want money for its own sake but for the magic that money can perform. It can be turned into practically anything--except human love. Love was a subject of great importance to D. H. Lawrence, as can be seen in many of his works. Paul is young. He doesn't realize that he can't buy his mother's love no matter how much money he makes. He ends up killing himself in the attempt to make more and more money to satisfy his mother's insatiable greed. She can spend money faster than he can make it. The rocking-horse, which must have cost a lot of money, is a good symbol for his plight, because it is only a wooden horse and can't take really take him anywhere, no matter how hard he rides.
Money has never made man happy, nor will it, there is nothing in its nature to produce happiness. The more of it one has the more one wants.