Grant writes about the The Fall of the Roman Empire, in his book by that title. He focuses on “the decay wrought by clinging to the alluring fantasy that past success guarantees future success, without any nasty sacrifices by the ruling elites.”

"Enmeshed in classical history, all [the Roman] can do is lapse into vague sermonizing, telling other Romans, as many a moralist had told them throughout the centuries, that they must undergo an ethical regeneration and return to the simplicities and self-sacrifices of their ancestors.

There was no room at all, in these ways of thinking, for the novel, apocalyptic situation which had now arisen, a situation which needed solutions as radical as itself. His whole attitude is a complacent acceptance of things as they are, without a single new idea.

This acceptance was accompanied by greatly excessive optimism about the present and future. Even when the end was only sixty years away, and the Empire was already crumbling fast, Rutilius continued to address the spirit of Rome with the same supreme assurance.

This blind adherence to the ideas of the past ranks high among the principal causes of the downfall of Rome. If you were sufficiently lulled by these traditional fictions,

there was no call to take any practical first-aid measures at all."

“Roman elites in Gaul were still writing letters to one another complaining of the breakdown of everyday life right up until the system collapsed.”