In the drawing-room Miss Crawford was also celebrated. Her merit in being gifted by nature with strength and courage was fully appreciated by the Miss Bertrams [...] (7.23).
This novel is, in many ways, a giant running commentary on the whole nature vs. nurture debate. Are people born with their personalities, or are their personalities formed by circumstances and surroundings? The narrator here notes that Mary is naturally strong and bold, which contrasts to the passive and weak Fanny.
"Why, child, I have but this moment escaped from his horrible mother. Such a penance as I have been enduring, while you were sitting here so composed and happy! It might have been as well, perhaps, if you had been in my place, but you always contrive to keep out of these scrapes" (10.27).
Julia is annoyed with Fanny for managing to get herself out of awkward situations just by doing nothing at all. Fanny is never in the thick of things, good or bad. Instead, she's often literally sitting on the sidelines.
Fanny looked on and listened, not unamused to observe the selfishness which, more or less disguised, seemed to govern them all, and wondering how it would end (14.4).
Fanny looks and listens here without interacting. It's almost as though she's watching a TV show. It's notable that Fanny is "amused" by everyone around her. Her amusement implies a bit of arrogance, though – rather than participate, Fanny just sits around and judges everyone else, to some degree.
"Me!" cried Fanny, sitting down again with a most frightened look. "Indeed you must excuse me. I could not act anything if you were to give me the world. No, indeed, I cannot act" (15.47).
Fanny's statement that she "cannot act" had a significant double meaning. Taken at face value, Fanny is saying that she can't participate in the play. But if we take "act" to refer to action, as opposed to getting on the stage in a theater, then Fanny is basically declaring that she's totally passive here. It's also notable that she says "cannot" instead of "will not" or "should not." "Cannot" implies that she has no choice in the matter and that she's somehow physically or mentally or emotionally incapable of "acting."
"But I do look down upon it, if it might have been higher. I must look down upon anything contented with obscurity when it might rise to distinction" (22.42).
Mary frequently praises bold, active people throughout the book and seems to judge and condemn people who aren't proactive. This particular statement is targeted at Edmund, since Mary sees his chosen profession as somehow "beneath" him.
"There, I will stake my last like a woman of spirit. No cold prudence for me. I am not born to sit still and do nothing. If I lose the game, it shall not be from not striving or it" (25.25.).
This is the best thematic statement for activity and action in the whole book, and it's also the statement that best characterizes Mary. It's interesting that Mary often characterizes herself through her own speech and dialogue. This is unusual in this novel – many characters, like Fanny, often don't speak at all and are characterized by the narrator. Mary is active even in how she presents herself to the world.
[Fanny's] diffidence, gratitude, and softness, made every expression of indifference seem almost like an effort of self-denial [...] (33.6).
Fanny is so passive and mild-mannered that she often runs the risk of being misunderstood by those around her. Being passive may seem safe, but it can be just as dangerous as being active.
Susan tried to be useful, where she could only have gone away and cried; and that Susan was useful she could perceive; that things, bad as they were, would have been worse but for such interposition [...] (40.4).
Susan provides a great "what if" contrast to Fanny. We have to question whether or not Fanny would still have been as shy and passive as she is if she had grown up in Portsmouth instead of at Mansfield Park.
Crawford was excessively pleased. If Lady Bertram, with all her incompetency and languor, could feel this, the inference of what her niece, alive and enlightened as she was, must feel, was elevating (34.18).
This is a very funny view of Lady Bertram, who is so passive that she seems like she's sleeping through life. Though both are passive, Lady Bertram's "languor," or bland indifference to everything, contrasts with Fanny's brand of passiveness, which has more to do with her low self-esteem and her shyness.
She could not turn her eyes from the meadow, she could not help watching all that passed. At first Miss Crawford and her companion made the circuit of the field, which was not small, at a foot's pace; then at her apparent suggestion, they rose into a canter; and to Fanny's timid nature it was most astonishing to see how well she sat (7.16).
The riding scene provides a clear symbolic contrast between Mary and Fanny. The way they ride is representative of the way they live their lives. Mary is a bold rider, able to race around quickly. Fanny rides at a snails pace on her old pony and is here stuck standing still and watching the more active Mary.
He hardly knew whether there were any difference in her spirits or not. She was always so gentle and retiring, that her emotions were beyond his discrimination. He did not understand her; he felt that he did not [..] (37.1).
Once again, Fanny's passiveness and her constantly gentle manner confuse people, in this case Sir Thomas. Since Fanny rarely expresses herself or her emotions, she's a complete mystery to those around her and is often misunderstood.