Aristotle’s unease appears visibly when he deals with monarchy.  He establishes five kinds ; he differentiates them not by their form of constitution, but by incidental things like the prince’s virtues or vices, or by foreign things, like the usurpation of tyranny or the succession to tyranny.
Aristotle places among the monarchies both the Persian empire and the kingdom of Lacedæmon. But who does not see that one of them was a despotic state, and the other a republic ?
The Ancients, who were unfamiliar with the distribution of the three powers in the government of one man alone, could not conceive a clear notion of monarchy.