The decline of Rome was the natural and inevitable effect of immoderate greatness. Prosperity ripened the principle of decay; the cause of the destruction multiplied with the extent of conquest; and, as soon as time or accident and removed the artificial supports, the stupendous fabric yielded to the pressure of its own weight. The story of the ruin is simple and obvious: and instead of inquiring why the Roman Empire was destroyed we should rather be surprised that it has subsisted for so long.
Edward GibbonBut in almost every province of the Roman world, an army of fanatics, without authority and without discipline, invaded the peaceful inhabitants; and the ruin of the fairest structures of antiquity still displays the ravages of those barbarians who alone had time and inclination to execute such laborious destruction.
Edward Gibbon[A] military force was collected in Europe, formidable by their arms and numbers, if the generals had understood the science of command, and the soldiers the duty of obedience.
Edward Gibbon