لا تُغزى الحضارة العظيمة من الخارج، ما لم تكن قد دمّرت نفسها من الداخل. وكانت أسباب انحدار روما الجوهرية كامنة في شعبها وأخلاقه، وصراعه الطبقي، وكساد تجارته، واستبداد بيروقراطيته، وضرائبه الخانقة، وحروبه المنهكة.

“A great civilization is not conquered from without, until it has destroyed itself from within. The essential causes of Rome's decline lay in her people, her morals, her class struggle, her failing trade, her bureaucratic despotism, her stifling taxes, her consuming wars.”Will Durant — The Story of Civilization: Caesar and Christ, a history of Roman civilization and of Christianity from their beginnings to A.D. 325 (1944)