Literature can be a very effective form of social commentary. Moreover, it can motivate people to change their social reality through an increase of awareness.
When we read a story that resembles our own reality, we are able to gain some perspective because of the distance that we put between the characters and us. It can also highlight aspects of our social situation that we had not noticed before.
A common example is Uncle Tom's Cabin, a novel by Harriet Beecher Stowe, which greatly contributed to the social condemnation of slavery. Similarly, George Orwell's novels, such as Animal Farm and 1984, have been very relevant in helping people realize the dangers of extremism and totalitarianism.