From the 16th to the 18th century， the idea of universal monarchy was a fundamental theme in European political imagination and thought. In the 16th century， the vast empire established by Charles V and Spain’s overseas expansion reignited the European political imagination of a universal monarchy. French and Italian humanist intellectuals such as Guillaume Postel and Tommaso Campanella invoked Christian universalism to argue for the divine mission of a universal monarchy. By the 17th century， influenced by the political discourse of reason of state， French political figure Henri de Rohan and Holy Roman Empire diplomat François-Paul de Lisola discussed universal monarchy from the perspectives of geopolitics， national interest， and the law of nations. In the early 18th century， Montesquieu elaborated on the historical significance of modern commerce and civilization in his critique of universal monarchy， placing his hopes for peace and enlightenment in the interactions and interdependence among nations.