How do you cause the fall of a mighty civilization? First you introduce the rise of a new religion. At first you decree tolerance of the new religion; then as time passes, you allow the new religion greater and greater influence until it becomes the official state religion, and undermines the country's long held traditions. Second, you separate the empire into two fundamentally different ethnic groups speaking different languages and having different beliefs and values. Over time you begin to show preference for the new group over the old until the new gains control from the old. Third, you introduce a lack of production, a trade deficit, and devaluation of your currency to pay off state debts. Finally, you cut the size of your military, and introduce political changes to its function. We should have learned this lesson 1700 years ago when Constantine implemented these changes, and Rome began to decline and eventually fell due to these very reasons. I think that if you try, you can find some parallels with our modern day American society.