Not only is bitter, brutal, bloody struggle not the single, nor the chief explanation of general evolution, but it is particularly not the chief explanation of human evolution, despite our origin and earlier life in Glacial or pre-Glacial Time as "animal among animals," and despite the stream of ever more diluted inheritance from tiger and ape ancestors that flows with us, as we move through the ages, changing, ever-changing, as we move. The simplicity of the explanation of human nature and human life from origins makes its appeal to all of us, and especially to those de-spiritualized ones of us who find in pure mechanistic conceptions a satisfying and ultra-economical explanation of every complex and difficult problem. But it is a dangerous explanation, leading us to be blind to many facts that are, if we are honest in our seeing, quite clearly before us. No matter when or where we may have begun the course of our truly human evolution we have come an immensely long way, a way so long that we have, we may say, almost no right at all to try to interpret our condition of today by the light of our condition in the beginning. And we have come to this point by the interjection into our nature by natural mutation, or conscious self-effort, of elements that were essentially foreign to our ancestors of the beginning days. We have, indeed, in our evolution a sort of double line; one that we may call our natural evolution, concerned with our physical characteristics and the fundamentals of our mental and social traits, and like all natural characters carried along in the race by heredity; and the other, that we may call our social or moral evolution, made possible, to be sure, only by the stage of our natural evolution, but concerned chiefly with various acquired mental and social characters, which are not an integral part of our heredity, but depend on speech, writing, education, precept and practise for transmission from one generation to the other, and, thus, for perpetuation and expansion in the race. This social evolution, added to a natural evolutionary development of the social or altruistic habit based on the advantage of the mutual aid principle as opposed to the mutual fight principle, has had an amazingly swift flowering since the earlier days of human prehistory, and today contains all the present expression and future promise of man's higher evolution. It has its roots in all of the best of man's natural traits, and acts as a powerful inhibitor of the worst of them. It finds its natural validity in the great strength it adds to man's position in Nature, for it permits a much swifter and more extreme development of human possibilities than would be possible by the slow processes of natural evolution. That which would take many generations to incorporate into our natural heredity can be put quickly into our social inheritance and still be hardly any the less powerful in its control of our life.