Machiavelli brings over one and a half millennia of monarchical encroachment upon republican territory to a categorical halt in the opening sentence of his first chapter:

Machiavelli divides, and his division demolishes the cherished claim of the Roman theory of monarchy that the Roman res publica had been saved by the institution of a prince at its head. The single most potent ideological weapon which monarchies had wielded since the thirteenth century in advancing the argument for princely rule on the Italian peninsula is thereby snapped in two. As far as Machiavelli's theory in De principatibus is concerned, whatever else a prince may rule, it is never said to be a republic and whatever else a prince may be, he is certainly not its mind. A pivotal part of the case which had been put forward for hundreds of years against neo-classical republicanism has been dismissed by means of a definition. Machiavelli has begun to generate a controversial typology of states which will usher in a new political grammar.

The definition proceeds, but Machiavelli delays revealing the differentia which he has used to divide states which are called republics from those which he is naming as principalities. Instead he starts to subdivide the states called principalities. In so doing he begins to clarify the defining property of the principality: