Purpose of Literature

“Authors tend to write more miserable books about 10 years after an economic downturn, a study has claimed.”
“Researchers compared the number of times certain words appeared in more than five million books to certain periods in American and British history. They found that the frequency of words expressing sadness reflected the economic conditions in the 10 years before a book was written.”
“The results suggest quite clearly that, contrary to post-modern literary theory, literature serves a purpose. It informs people about the human condition, and the content adapts to the conditions of the time.”

From: http://www.telegraph.co.uk/culture/books/booknews/10559375/Economic-downturns-fuel-sad-books-claims-study.html