Book: The Consolation of Philosophy (Penguin Classics)
Thesis: Boethius believes that God is all-powerful, all-knowing, and good. But if his view is correct, then why do bad things exist at all? Why is there evil in the world?
Remember to organize your points around a specific thesis, which you defend with reasons and evidence, and to strive for clarity and concision. The ideal essay contains nothing irrelevant, and it should be more than a mere summary of the material. Recall that to be interesting, you need to try to prove something.
Secondary readings are certainly allowed in researching your topic, but they are not required. What matters most is a clear, sound argument. If you seek philosophical background, a number of valuable articles on philosophical topics can also be found online in the Stanford Encyclopedia of Philosophy and in the Internet Encyclopedia of Philosophy.