Read Cicero. He was remarkably prescient. He predicted that when the simple virtues or pietas of the Republic were no longer held by the people, Rome would not be conquered but would rot from within. John Adams came to the same conclusion regarding the American Republic. Character has always been at the core of any successful civilization. Historically the avid embrace of neo pagan, hedonistic decadence ( a perverse permutation of epicureanism) has been a constant of every collapse. Our time is no different.
Did any romans of antiquity call for open borders?