One theme could be expressed by a cliché—like "You can't teach an old dog new tricks" or "A leopard can't change his spots."
In reading V.S. Pritchett's "The Fly in the Ointment," it is plain to see that the two main characters are extremely different. From the first page, we note that the son (Harold) has no desire to bring the topic of money up to his father.
Better not arrive in a taxi, he was thinking. The old man will wonder where I got the money.
We discover that money is a major cause of strife. And yet, the son puts things into perspective and decides that none of that is important at the moment.
Suddenly all the money quarrels of the family, which nagged in the young man's mind, had been dissolved. His dread of being involved in them vanished. He was overcome by the sadness of his father's situation.
As the father prepares to close the business, Harold arrives to offer moral support. We also learn, however, that the father has little respect for his son as a general rule.
"Come in, Professor," said the father. This was an old family joke. He despised his son, who was, in fact, not a professor but a poorly paid lecturer at a provincial university.
Because of the father's long-standing disregard for his son, Harold must be surprised at his father's greeting when he arrives.
"Hullo, old chap. This is very nice of you, Harold," said the old man shyly, stepping back from the door to let his son in, and lowering his pleased, blue eyes for a second's modesty.
Words like "shyly" and "modesty" are not generally attributed to the old man, but he continues—offering his son tea, seeing to his comfort and apologizing for the bare surroundings. In fact, except for knowing that the father despises the son, the father's initial interactions toward Harold speak of a caring nature.
However, a glimpse of that critical man comes out when he makes a fuss over his son's advancing baldness. Certainly Harold knows about his hair, but his father not only points it out—he goes on and on about it—all the while saying that he is not being critical. Still, Harold being a concerned son (which seems to be more than the older man deserves) has put aside any resentment he might harbor for his father's previous treatment, to support him at this difficult time.
Overcome by sadness for his dad, Harold suggests that if there were any way to get money to his father if he were ever in dire straits, he would do whatever he could, though he really has nothing—in truth, he is embarrassed by his own "poverty."
"I'm not rich. None of us is...we can't do anything...well, if it is ever a question of—well, to be frank, cash, I'd raise it somehow."
No sooner is the son's wish out of his mouth, than his father loses any sense of gentleness or humility, but pounces on his son's words like a rabid dog after a steak:
"Raise it?" said the old man sharply. "Why didn't you tell me before you could raise money? How can you raise it? Where? By when?"
Though circumstances may have diminished the old man for a short while, the potential of getting any money, even from his son who has nothing, whisks the father back to his former aggressive self. Pritchett uses foreshadowing at the beginning when Harold thinks upon arriving in a hired cab:
All the same, knowing his father, he had paid off the taxi and walked the last quarter of a mile.
Knowing his father, Harold practiced caution...with good reason. This "leopard" had not changed his spots at all!