IX.2 That the federative constitution must be composed of states of the same kind, especially of republican states
The Canaanites were destroyed because they were small monarchies which had not confederated, and did not defend themselves in common. For confederation is not the nature of small monarchies.
The federative republic of Germany is composed of free cities and small states under the rule of princes. Experience shows it to be more imperfect than those of Holland and Switzerland.
The spirit of monarchy is war and aggrandizement ; the spirit of the republic is peace and moderation. These two kinds of government cannot coexist except by force in a federative republic.
Thus we see in Roman history that when the Veientes  had chosen a king, all the small republics of Tuscany abandoned them. All was lost in Greece when the kings of Macedonia obtained a position among the Amphictyonies.
The federative republic of Germany, composed of princes and free cities, subsists because it has a head, who is in some sense the magistrate of the union, and in some sense the monarch.