“Subtle and firm” was C.S. Lewis’ view of Jane Austen as a moralist. Apart from being the Empress of English, Austen is a beautifully lucid observer of human psychology.
Jane Austen, Sense and Sensibility [of Marianne]
Elinor had not needed this to be assured of the injustice to which her sister was often led in her opinion of others by the irritable refinement of her own mind, and the too-great importance placed by her on the delicacies of a strong sensibility and the graces of a polished manner. Like half the rest of the world, if more than half there be that are clever and good, Marianne, with excellent abilities and an excellent disposition, was neither reasonable nor candid. She expected from other people the same opinions and feelings as her own, and she judged of their motives by the immediate effect of their actions on herself. Thus a circumstance occurred while the sisters were together in their own room after breakfast which sank the heart of Mrs. Jennings still lower in her estimation; because, through her own weakness, it chanced to prove a source of fresh pain to herself, though Mrs. Jennings were governed in it by an impulse of the utmost goodwill.