If you decided to follow the easiest and the shortest path – go to the library and grab every book you see (not literary! Use your book list your teacher was supposed to give you at the beginning of the semester, or particularly for this assignment, - most likely he/she wants you to be guided by them, or you can follow advices of librarians if some books are not available, or you are desperate to find fresh ideas in those sources). When you are sitting and reading everything you could find, start forming your opinion, take notes and write down possible quotations. It is better if you can come up with an opinion on a primary source, not just rewriting somebody's ideas from a critic book.
A good essay is a hard thing to do, not the impossible one though. You always have to work hard on what is good, and essay is not an exception. Remember that if you came up with nothing after all, you always have people who have fresh ideas 24/7 and will be glad to help you