It is difficult to create an empire but it is easy to provoke a squabble. It is difficult to convince people that they are wrong but it is easy to persuade them that other people are not right. All it takes is to replace reason with emotion, the most productive being fear, anger, resentment, or guilt. ("Only such a mighty guilt as Augustine's could have produced such a marvelous saint." The Book of Rhino)
Reason which produces character and rational behavior is difficult to contend with if one is intent on building an empire. Reason has a moral center and insists on sifting through the facts itself - instead of relying on another person's interpretation. Reason is not easily swayed by emotion even in the face of self-interest. Whenever there is a critical mass of reasonable people to reckon with, building an empire is a lost cause. It is much easier to appeal to emotion. Set the senators squabbling among themselves.