Moral Criticism and Dramatic Construction (~360 BC-present)
Plato
In Book X of his Republic, Plato may have given us the first volley of detailed and lengthy literary criticism. The dialog between Socrates and two of his associates shows the participants of this discussion concluding that art must play a limited and very strict role in the perfect Greek Republic.
Richter provides a nice summary of this point: "...poets may stay as servants of the state if they teach piety and virtue, but the pleasures of art are condemned as inherently corrupting to citizens..." (19).
One reason Plato included these ideas in his Socratic dialog because he believed that art was a mediocre reproduction of nature: "...what artists do...is hold the mirror up to nature: They copy the appearances of men, animals, and objects in the physical world...and the intelligence that went into its creation need involve nothing more than conjecture" (Richter 19).
So in short, if art does not teach morality and ethics, then it is damaging to its audience, and for Plato this damaged his Republic.Given this controversial approach to art, it's easy to see why Plato's position has an impact on literature and literary criticism even today (though scholars who critique work based on whether or not the story teaches a moral are few - virtue may have an impact on children's literature, however).