Matilda now asked, who was this Agnes with whom the Prioress was thus incensed, and what connection She could have with Ambrosio. He related her adventure; and He added, that since that time his ideas having undergone a thorough revolution, He now felt much compassion for the unfortunate Nun. (p. 230)
Ambrosio's compassion has a different genesis that that typical of compassionating sensibility. Agnes's sensible plea was easily rejected by the monk earlier, who feels differently now because his "ideas" have undergone a "revolution." Pity for Agnes, then, does not BRING the monk to a different moral state, according to the regular functioning of sensibility. Rather, Ambrosio changes his mind first; pity is a secondary response. The moment of sensibility is a product of a dramatic structure that doesn't REQUIRE that moment. Treated as such, sensibility can be at best a sign of community, not an engine for it.
Pity is a sentiment so natural, so appropriate to the female character, that it is scarcely a merit for a Woman to possess it, but to be without it is a grievous crime ... However, though he blamed her insensibility, He felt the truth of her observations; and though He pitied sincerely the unfortunate Agnes, He resolved to drop the idea of interposing in her behalf. (p. 232)
We have just seen, some paragraphs ago, that pity is not natural; at least in Ambrosio's case, it is acquired by virtue of a sympathetic association that may or may not be possible. But pity is "natural" to the female character. The pity that Ambrosio expects from Matilda, then, must precede or occasion sympathy; it becomes a socially forceful capacity, since it starts in nature, not in a predetermined social relation.