Yet as the Crawfords prolonged their stay and came to know Fanny and Edmund better and better, they began to get an inkling of everything that they'd been missing. Henry saw something In Edward that he wished he could find in himself, and something in Fanny that he wished he could have for himself. As for Mary, when she did at last tear herself away from Mansfield to pay a long-delayed visit to another friend, she had this to say to the heroine: "Mrs. Fraser has been my intimate friend for years. But I have not the least inclination to go near her. I can think only of the friends I am leaving...You have all so much more heart among you, than one finds in the world at large." "Heart"--Mary's stammering attempt to name the things she was starting to learn how to value: moral seriousness, depth of feeling, constancy of purpose. Inner riches--things you can't buy, things you have to earn. The woman who'd thought she had everything was discovering just how destitute she really was.
Whereas Henry and the rest, always able to command amusement, were constantly dogged by the threat of boredom, Fanny had created a rich inner life for herself. The East room, her little space upstairs, was like a diorama of her mind, a place where she could always find "some pursuit, or some train of thought...Her plants, her books,...her writing desk,...her works of charity and ingenuity." She was quiet and shy, yes, but she had a lot going on beneath the surface. For that was the big surprise about her, one that it took me a very long time to see. Mary, lovely and charming, was far better able to incite emotions, but Fanny felt them that much more keenly. She may have been prudish and prim, but she was also, of all things, intensely passionate.
--William Deresiewicz, from A Jane Austen Education