In the case of tribes it is impossible to make out completely why their governments were mixed, constitutional, and normal, because we know but little about the tribes and nothing of their history. But at any rate we may observe that the tribes were militant communities engaged in a constant struggle for existence with other similar communities, and that in such communities it is essential to the safety of each and all of their members that all the classes which contribute to the fighting strength should be kept contented and zealous in the common cause, and that therefore it is necessary that none of those classes should be oppressed and that each should have its fair share in determining their common action. In the case of city states the reasons why the governments were unmixed, absolute, and abnormal are best seen contrasting a city state with a larger political community: for example, England in the middle ages. In that large political community it was impossible, owing to the size of the territory, the importance of the country districts, and the diverse characters of different districts, for any single person or class to engross all power and become the sole ruler. The size of the territory necessitated the existence of local rulers or magnates, the barons: and diversities of local character made each locality inclined in case of need to act for itself under its own baron. The result was that if any person or class attempted to become omnipotent and oppressive, some of the local districts rose in revolt under their barons and the attempt ended in failure. In a city state all the circumstances were different: the country districts had no strength or importance, the power, whether it was a person or a class, that ruled in the city, met with no resistance from outside the city, and, owing to the small size of the territory, had all its enemies within its reach, and could easily destroy them unless they chose to go into exile. In my second chapter it was stated tentatively and without proof that there is an intimate connexion between the form of a political body and the form of the government by which it is ruled. The connexion between form of political body and form of government has now been traced in the case of the Greek tribes and cities, and it has been shown that the assumption which I made when I divided the Greek governments before the battle of Chæroneia into tribal governments and city governments was one for which history affords justification. CHAPTER VII. THE ACHÆAN LEAGUE[249]. [249] The chief modern authorities for the history of the Achæan League are Bishop Thirlwall in the eighth volume of his _History of Greece_, and Professor Freeman in his _History of Federal Government in Greece and Italy_. I have compiled this chapter, after reading what those authors say on the subject, from the books by ancient writers which they cite.