How did montesquieu's ideas about government differ from his predecessors' classical divisions of monarchy, aristocracy, and democracy?

Differing from his predecessors' classical divisions of monarchy, aristocracy, and democracy, Montesquieu stated that there are two types of government which exists: the sovereign and the administrative. He opined that the administrative powers were divided into the executive, the judicial and the legislative, and that these powers must be separate from one another and dependent upon one another. This idea is what has come to be known in modern times as separation of powers.