We come at length to the biological interpretation of human social evolution, in so far as this may be expounded in a simple and concise form. The comparative method must be employed in order to discover the fundamental attributes of savage, barbarous, and civilized communities which seem to differ so considerably in their complexity of social structure, and in order also to show that such basic elements are like those of communities formed by lower animals, and are equally the products of natural evolution. This whole subject seems to be exceedingly complex, because in our daily contact with others of our kind and in our occasional views of foreign races like our own, the smaller details occupy our attention, diverting it from the great basic principles according to which every society is organized and operates. But when once the major elements have been discovered in civilized and more primitive nations, the secondary and less essential phenomena fall into their proper relations, and a statement of the whole process of development becomes relatively simple. So much space has been devoted to lower types of communal organisms in order to learn what the fundamentals are, and not merely to provide analogies that may be useful hereafter. It now remains to arrange the evidences of social progress during the history of mankind itself, and to bring such human facts into relation with what has been discovered in lower nature. It is helpful to begin this part of the subject by asking ourselves what is already part of common knowledge about human history. Do we know of any civilized nation that is absolutely stable and unvarying in social structure, or one that has remained unchanged throughout historic time? The answer must be negative, for in no case does the past disclose an example of permanence in social or in any other respect; monarchies and republics are plastic like the human frame itself. The American Commonwealth is a relatively young social organism, and it is an easy task to trace its growth from beginnings in the diffuse and uncorrelated colonies of pre-Revolutionary years. Those colonies that were formed by English settlers were transplanted outgrowths from a civilized social parent which in its turn had clearly evolved from the state of King John's time and the still cruder form it had under King Alfred.