This is a large and comprehensive subject, and embraces such principles as the Centralization of States; the Co-operation of States; Monogamic Marriage; Unions; Free Trade, and many others equally important. We have already noticed that cohesion is a well-known property of matter; that its influence is not confined to the regions of physical sciences; and that it is the manifest duty of all governments to increase the force of cohesion. Various methods have been tried to accomplish this purpose. The principle of Feudalism was one of the earliest attempts to produce the cohesion of the nation; and, in an elementary condition of society, it was partly successful. The theories of 'Divine Right' and 'Social Contract' were other methods which have been adopted; and the unity of the Christian Church has been the great means of producing the cohesion of the State in olden times; and its aid may be again required for the same beneficent object in future complications and social disruptions. But it is always advantageous in scientific pursuits to go back to first principles; and we will adopt that method in our present investigations. The social unit is the family; the multiplication of families makes the tribe; the multiplication of tribes makes the State; and, therefore, we shall not be far wrong if we consider the family tie as the first principle of political cohesion. I am in agreement with several learned thinkers upon this subject when I say that marriage is a most important political factor; and as marriage cannot take place without women, it is evident that women play a very important part in promoting the cohesion of the State.