Foster explains why most literature can be called political. summarize his argument

Foster argues that when an author create a literature, that author will somehow put their point of view/perception on what is considered good/bad for the society, how character should behave, etc.
This point of view will persuade the readers into a certain mindset that will drive them into a certain pollitical affiliation that support that mindset.
Therefore, He conclude that most literature can be called a political.