Nicolo Machiavelli, tr. W.K. Mariott, Il Principe courtesy of Project Gutenberg:
Chapter IV Why the Kingdom of Darius, Conquered by Alexander, did not Rebel Against the Successors of Alexander at his Death
Considering the difficulties which men have had to hold to a newly acquired state, some might wonder how, seeing that Alexander the Great became the master of Asia in a few years, and died whilst it was scarcely settled (whence it might appear reasonable that the whole empire would have rebelled), nevertheless his successors maintained themselves, and had to meet no other difficulty than that which arose among themselves from their own ambitions.
I answer that the principalities of which one has record are found to be governed in two different ways; either by a prince, with a body of servants, who assist him to govern the kingdom as ministers by his favour and permission; or by a prince and barons, who hold that dignity by antiquity of blood and not by the grace of the prince. Such barons have states and their own subjects, who recognize them as lords and hold them in natural affection. Those states that are governed by a prince and his servants hold their prince in more consideration, because in all the country there is no one who is recognized as superior to him, and if they yield obedience to another they do it as to a minister and official, and they do not bear him any particular affection.