I read an answer to a question about liberalism in which the answer...?

The fall of the Roman Empire only has relevance to Liberalism in that it was an important historical event that shaped the development of history and western thought. The main lesson learned from the fall of the Roman Empire was learned by the Catholic Church. The Church had detected the strong instabilities in the Empire and distanced itself from the monarchy so that, if the Empire did fall, the Church would not be dragged with it. It's this separation which institutionalized an inherent separation of Church and State in the Catholic tradition which continues to this day. Today, though the pope technically rules Vatican City, he has no set authority over politics or political boundaries.