Kyklos
The kyklos (Ancient Greek: κύκλος , "cycle") is a term used by some classical Greek authors to describe what they considered as the cycle of governments in a society. It was roughly based on the history of Greek city-states in the same period. The concept of the "kyklos" is first elaborated by Plato, Aristotle, and most extensively Polybius"." They all came up with their own interpretation of the cycle, and possible solutions to break the cycle, since they thought the cycle to be harmful. Later writers such as Cicero and Machiavelli commented on the "kyklos". Plato. Plato describes his  version of the "kyklos" in his work "Republic," Book VIII and IX. He distinguishes five forms of government: aristocracy, timocracy, oligarchy, democracy, and tyranny, and writes that governments devolve respectively in this order from aristocracy into tyranny. Plato's cycle of governments is linked with his anthropology of the rulers that come with each form of government. This philosophy is intertwined with the way the cycle of governments plays out. An aristocracy is ruled by aristocratic people whose rule is guided by their rationality. The decline of aristrocracy into timocracy happens when people who are less qualified to rule come  to power. Their rule and decision-making is guided by honor. Timocracy devolves into oligarchy as soon as those rulers act in pursuit of wealth; oligarchy devolves into democracy when the rulers act on behalf of freedom; and lastly, democracy devolves into tyranny if rulers mainly seek power. Plato believes that having a philosopher king, and thus having an aristocratic form of government is the most desirable. Aristotle. Aristotle writes about the cycle of governments in his "Politics." He believes the cycle begins with monarchy and ends in anarchy, and that it does not start anew. He also refers to  democracy as the degenerate form of rule by the many and calls the virtuous form "politeia", which is often translated as constitutional democracy. All the philosophers believed that this cycling was harmful. The transitions would often be accompanied by violence and turmoil, and a good part of the cycle would be spent with the degenerate forms of government. Aristotle gave a number of options as to how the cycle could be halted or slowed: Polybius. According to Polybius, who has the most fully developed version of the "kyklos", it rotates through the three basic forms of government: democracy, aristocracy, and  monarchy, and the three degenerate forms of each of these governments: ochlocracy, oligarchy, and tyranny. Originally society is in ochlocracy but the strongest figure emerges and sets up a monarchy. The monarch's descendants, who lack virtue because of their family's power, become despots and the monarchy degenerates into a tyranny. Because of the excesses of the ruler the tyranny is overthrown by the leading citizens of the state who set up an aristocracy. They too quickly forget about virtue and the state becomes an oligarchy. These oligarchs are overthrown by the people who set up a democracy. Democracy  soon becomes corrupt and degenerates into ochlocracy, beginning the cycle anew. Polybius's concept of the cycle of governments is called anacyclosis. Polybius, in contrast to Aristotle, focuses on the idea of mixed government: the idea that the ideal government is one that blends elements of monarchy, aristocracy, and democracy. Aristotle mentions this notion but pays little attention to it. Polybius saw the Roman Republic as the embodiment of this mixed constitution, and this would explain why the Roman Republic was so powerful and why it would remain stable for a longer amount of time. Polybius' description of the anacyclosis  can be found in Book VI of his "Histories". Cicero. Cicero describes anacyclosis in his philosophical work "De re publica". His version of the anacyclosis is heavily inspired by Polybius' writings. Cicero argues, contrary to Polybius, that the Roman state can prevail and will not succumb to the harmful cycle despite its mixed government, as long as the Roman Republic will return to its ancient virtues ("mos maiorum"). Machiavelli. Machiavelli, writing during the Renaissance, appears to have adopted Polybius' version of the cycle. Machiavelli's adoption of anacyclosis can be seen in Book I, Chapter II of his "Discourses on  Livy". Although Machiavelli adopts the idea of the circular structure in which types of governments alternate, he does not accept Polybius' idea that the cycle naturally devolves through the exact same pattern of governments.