"Polybius's picture of the motors of political change is persuasive if not taken rigidly, and it provides a rationalization of Roman history: leaders who rise by their talents will (at least initially) live like their fellows and arouse no hostility, while those who inherit a throne will separate themselves from everyone else and arouse envy. They will be opposed by men of the upper class affronted by the insolence of their king—or kings, since Polybius knew that Sparta and Rome had been ruled by a collective monarchy. When they are overthrown, their aristocratic supplanters will rule in their stead. That aristocracies degenerate into oligarchies is the most common complaint against aristocratic governments, and often leveled at their modern descendants, the elected aristocrats who occupy the seats of power in the modern democratic world. Readers will find less persuasive Polybius’s claim that when an oligarchy is overturned, democracy invariably follows. He says that the memory of the tyranny of kings will be too fresh in everyone’s mind for there to be a reversal of the cycle from oligarchy to monarchy, but this is empirically unconvincing; it turns the unusual experience of Athens and Rome into a principle. We are all too familiar with situations in which a disgusted public turns to a dictator, though it has to be said in Polybius’s favor that “oligarchy-democracy-dictatorship” is perhaps the most common cycle of all."