But if Jane Austen could see that a world of frantic change was about to supplant the world of peaceful fixity she knew, why then does she allow the spirit of Mansfield, in the figure of Fanny, to triumph over the forces of change, as exemplified by the Crawfords? I think one could put it this way: to a world abandoning itself to the dangers of thoughtless restlessness, Jane Austen is holding up the image of the values of thoughtful rest. Aware that the trend was for more and more people to explore the excitements of personality, she wanted to show how much there was to be said for the ‘heroism of principle’. Mansfield Park is a stoic book in that it speaks for stillness rather than movement, firmness rather than fluidity, arrest rather than change, endurance rather than adventure. In the figure of Fanny it elevates the mind that 'struggles against itself’, as opposed to the ego which indulges its promiscuous potentialities. Fanny is a true heroine because in a turbulent world it is harder to refrain from action than to let energy and impulse run riot.
Tony Tanner, “The Quiet Thing”: Mansfield Park