Important, [he repeats, not quesioningly or mockingly, but thoughtfully. Her calling it that at least makes it clear what she meant by it.
Sebastian doesn't really understand doing good for its own sake, admittedly, but he's known many humans that swear by it (usually there's lip-service involved to various degrees, but...). In the end, he supposes, convictions like that are only more fragile, less rational versions of something like his own aesthetics.]