The kyklos (Ancient Greek: κύκλος [kýklos], "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.