Austen's moral thought occupies a transitional phase between 18th C christian theologians she looked to for inspiration and rational moral sense we see in a George Eliot or Henry James. On the one hand, there are absolute moral principles you must adhere to regardless of circumstances; these are "rational" standards set by society. On the other hand, there are duties and obligations which arise not from a notion, for example, like Noblesse Oblige, or from consultation with others, but come from reflection, from withdrawing from social strictures to consult our private conscience. This connects Jane Austen's thought with a distinctly Protestant dimension.
Morally "just" conduct, then, is inseparable from respect, compassion, and sensitivity, and so from manners, civility or propriety. Civility means not just coughing in someone's face, but not being boorish, arrogant, long-winded, or conceited. Propriety suggests a sense of what is proper to oneself and to others—what is proportionate, due, fit, "just." Considerations of respect and considerateness are involved.
For Jane Austen, you have to be educated in virtue, so it is often hard work, in contrast to the Romantic view that it is a matter of spontaneous impulse or innate "sensibility" or feeling.
Edmund Burke wrote that "Manners are more important than laws." This is the rule of thumb for the kind of gentry that Jane Austen praises. By translating laws and rules into attractive forms of behaviour, men and women come to appreciate their utility. So what secures the allegiance of the lower classes is not simply a code of conduct forced on them by their "betters," but the graceful, well-ordered, socially responsible forms of an entire way of life. For Jane Austen, then, culture not coercion is the key to a sound society.
Indeed, you can see in Austen that the form of the realist novel is connected to a change in morality: roughly speaking, from a matter of timeless codes and...