I recently heard about an interesting controversy between Martha Nussbaum and a Supreme Court Justice, regarding whether literature is morally improving.
There's definite intuitive attraction to the idea that literature can produce moral insights. Doesn't reading Jane Austen show us how someone can be behaving in a transparently selfish way, while only citing to themselves the loftyest motives - and hence make us aware of this possibility? Or doesn't Lolita show us how passionate love is compatible with persistent cruelty? It certainly seems prima facie plausible that vividly imagining and thinking about cases like this would help you avoid similar hypocracy or cruelty in your own life.
However, the judge then made the nice point that we don't seem to expect students of literature to be more moral than students of related fields. So if literature is really so morally improving, why don't we expect to see good effects ?
Here's one possibility: literature can make us aware of subtle ways to be cruel or self-deceptive (or kind or sensitive) to one another. Insofar as it does this, it may tend to make people behave better e.g. by making them notice when they are considering doing something similar.
However, the main barrier to acting well in ordinary life may be more a matter of organizational skills and overcomming akresia than a matter of recognizing subtle morally relevant aspects of one's situation. It doesn't take any subtle act of imagination to recognize that you could help people by donating to unicef, and to find something attractive about this prospect. This puts a limit on the extent to which we should expect moral improvement from literature.
And, in fact, it suggests a way in which literature might actively have the opposite effect. Thoughtful imaginative engagement with the prospect of committing adultery, or spending lots of money touring the ruins of ancient China, can also make someone feel more keenly how much one is giving up in forgoing these. Insofar as literature can make us aware of morally salient features of a situation, it can also make us aware of hedonistically or self-interestedly salient features. If Madam Bovary and Camera Obscura engage our thoughts and imagination with certain aspects of adultery, Marvel's "let us roll all our strength and all our sweetness up into one ball" (or Chekov's The Lady With a Lapdog) engages our thoughts and imagination with quite different ones!
Thus, literature might be morally enlightening, but not -on net- morally improving.