Structural weaknesses in Rome’s power? Greek historians’ views on Roman stasis

Greek historians of the Roman Empire, from Polybius through Appian, admired the breadth and stability of the empire as an unprecedented achievement in human history, and devised innovative historiographical methods to write about it. Each believed that Rome’s eventual fall, if it ever would happen (Polybius explicitly said that it would, Dionysius of Halicarnassus and Appian of Alexandria were more circumspect), would originate from internal causes, not an external threat. Dionysius conveyed this subtly through his treatment of the foundational fratricide of the city. Polybius stated it openly in programmatic statements, but offered little detail or analysis to explain. Appian planted the idea by the very structure and plan of his history, in which five books on the Roman civil wars present an enigma and a theme.