英國歷史學家R G Collingwood曾指出，ㄧ些國家/朝代如南美Aztec是因外族侵入而滅亡，但ㄧ些如羅馬帝國不是像大多數人印象是外族如日耳曼侵入而滅，而是"ㄧ些子民不再認為現有的生活方式值得保留"
Societies may die a violent death, like the Inca and Aztec societies which the Spaniards destroyed with gunpowder in the sixteenth century; and it is sometimes thought by people who have been reading historical thrillers that the Roman Empire died in the same way, at the hands of barbarian invaders.
That theory is amusing but untrue.
***It died of disease, not of violence, and the disease was a long-growing and deep-seated conviction that its own way of life was not worth preserving.***
--R G Collingwood