In a short scene near the beginning of the novel, Dr. Grant and Mrs. Norris argue over whether the fruit of a peach tree on Mansfield Park’s property is tasty or not. Dr. Grant says its fruit is bad, but Mrs. Norris cannot accept that to be true when the tree’s genus means it’s supposed to be delicious, forming a metaphor about a person’s character and their upbringing:
“The tree thrives well beyond a doubt, madam,” replied Dr. Grant. “The soil is good; and I never pass it without regretting, that the fruit should be so little worth the trouble of gathering.”
“Sir, it is a moor park, we bought it as a moor park, and it cost us— that is, it was a present from Sir Thomas, but I saw the bill, and I know it cost seven shillings, and was charged as a moor park.”
“You were imposed on, ma’am,” replied Dr. Grant; “these potatoes have as much the flavour of a moor park apricot, as the fruit from that tree. It is an insipid fruit at the best; but a good apricot is eatable, which none from my garden are.”
This moment could be read as a subtle metaphor for how Mrs. Norris—and British society in this time period in general—assume a person’s heredity (and specifically their family’s social class), like a tree’s genus, determines their quality. Austen—through Dr. Grant—is pointing out the hypocrisy of judging people based on their background and not on their character. This point comes across most directly via the character of Fanny, who comes from a lower-middle-class background yet is the most well-mannered and moral character in the novel.
When Fanny is settling into daily life while visiting her family in Portsmouth, her mother (Mrs. Price) has no time for her. It becomes clear, over the course of Fanny’s stay in Portsmouth, that the tense relationship between her and her mother is a metaphor for the relationship between wealthy country people and lower-middle-class city people in England. Here Austen captures the ways in which the two women are unable to connect:
[Fanny’s] disappointment in her mother was greater; there she had hoped much, and found almost nothing. Every flattering scheme of being of consequence to her soon fell to the ground. Mrs. Price was not unkind—but, instead of gaining on her affection and confidence, and becoming more and more dear, her daughter never met with greater kindness from her, than on the first day of her arrival.
While Fanny was looking forward to visiting her mother after years of feeling like an outsider at Mansfield Park (being the only person who came from a lower-middle-class background), here she finds that she is an outsider in a lower-middle-class home, too. Without her noticing it, her sensibilities have changed—she does not move at the harried pace of the city people in Portsmouth, preferring to sit and spend idle time with her family. This, of course, is not possible for her parents, who have to work and provide for nine children without the assistance of servants. All of these dynamics combine to form a metaphor for the disconnection between lower-middle-class city people and wealthy country people more broadly.