How does literature shape or reflect a society?

Literature does both things; it shapes and also reflects the society we live in

Authors have different forms of writing. They could introduce you to a new idea, persuade you to their point of view (bias) and also influence people to do something new. Words are powerful, and can be used in many ways. For example if i introduce you to a new idea (like cats have 5 toes in the frontal paws and 4 toes in the back paws) you would share it with a friend. Now lets take it to a whole new level. There is a book called "fifty shades of gray" it has influenced the way of thinking of many women and men. Literature can shape the way we think. It can persuade us to believe things; we are eager to share what we find interesting. 

literature reflects our society. Throughout the years we had styles of writing that reflected the time period we were living in. In other words, when we lived through a crisis, a genre of writing was born. romanticism, Goth-ism, realism, naturalism, modernism, etc