Western societies from ancient Athens to imperial Rome to the French republic rarely collapsed because of a shortage of resources or because foreign enemies proved too numerous or formidable in arms - even when those enemies were grim Macedonians or Germans. Rather, in times of peace and prosperity there arose an unreal view of the world beyond their borders, one that was the product of insularity brought about by success, and an intellectual arrogance that for some can be the unfortunate byproduct of an enlightened society.