Ever since the Ancients began to expound their theories on the evolution and nature of civilised society, establishing what could most probably be called Western Political Theory, men and women of every era have offered their own contributions to the topic. But because the people concerned have almost all been familiar with the preceding generations" theories, they have sometimes introduced elements of those predecessors" work into their own. And they have also offered alternatives, rebuttal and criticism to the work of their predecessors or sometimes of their contemporaries. In this way we can see the ongoing conversation between political theorists down through the ages.
Sometimes we can immediately discern the conversation between the theorists, when one will refer to the work of another. This can be used as confirmation of the opinion of the referring theorist: .
Secondly, that an agrarian is dangerous unto a commonwealth is affirmed upon no slight authority, seeing Machiavel is positive that it was the dissension which happened about the agrarian that caused the destruction of Rome.
-The Commonwealth of Oceana.
Here we see James Harrington using Machiavelli as the authority for Harrington's assertions on agrarian law. This is not the only time we see Machiavelli cited as the authority on a piece of political theory, especially those concerning the republican school.
Rousseau also uses Machiavelli, although in a different way. His statement in Du contrat social about the necessity of a Lawgiver, along the lines of Lycurgus or Solon, at the establishment of any society is obviously "borrowed" from Machiavelli. This is merely a different form of the ongoing conversation, where the influence of a particularly great theorist percolates down through each succeeding generation, emerging in new theories sometimes hundreds of years later. Some would say that this could not be seen as a true conversation, because of the time gap that sometimes exists.