Okay, we're switching gears from literature of the Enlightenment to Romantic literature, and Goethe's Faust is the first masterwork from the Romantic period that you'll read.
Much of the nineteenth century's literature, the European variety collectively known as Romanticism, returns to some heavy, dark themes. Rather than exploring the outward world, as many eighteenth century authors were interested in doing, here you'll see an exploration of self, of personal integrity, of decision making, and the results that characterizes much of the literature from Europe at the time. Think about what was going on in the world at the time, and take a look at the time line on the companion website - you may find that there are some historical events that turned people's attention away from Enlightenment themes.
There is an excellent Faust study guide at http://webpages.shepherd.edu/maustin/engl209/Goethe.doc. For more information than you ever wanted about Goethe, see http://worldroots.com/brigitte/goethe1.htm.
Interpretations of Faust are many. Wikipedia's article comments on the various interpretations: http://en.wikipedia.org/wiki/Goethe's_Faust. As I wrote the assignment for the Unit 1 essay, I included Faust as a possible text. After reading it, you may be happy that you've escaped it 