Our book has no special chapter on the League of Nations itself. The idea pervades the whole, and the subject was treated in detail in the first volume of this series (_The Unity of Western Civilization_, 1915). The history behind the League offers a striking analogy to the other struggles for unity of which we have spoken. There is the same advance from the idea of a unity dictated and controlled by one mind to a unity of spirit arising from the free co-operation of many diverse elements all aiming at the same general good. Down even to yesterday it seemed to many minds a necessary condition that one man, gathering in his hands the resources of one great State, should from that centre dominate the world. And in the dawn of human history it was no doubt often true, the only way in which the world could then advance. This was true for Alexander, the prototype of all the Roman conquerors, and true, conspicuously, for the Roman empire at its best. But, after the break-up of the empire, unity of this type became a delusive mirage, misleading all who, like the Holy Roman emperors, sought to enjoy it again. By the time of Napoleon it had become an anachronism of the most dangerous and reactionary kind. The world was then too vast, the freedom of men and nations too various and deeply rooted. Meanwhile a real unity, stronger than before, had been forming beneath the surface and needed fresh institutions to body it forth. This movement for unity has been, as we have seen, precipitated by the war into visible and decisive action. It had been simmering for three hundred years in 'Great Designs', 'Projects of Peace', Treaties of Arbitration, and Hague Conventions. Among much that is doubtful in the future of the League, one thing stands out as a capital certainty. Without losing the very spirit of its being it can never become a satellite system, revolving round one dominant Power or even a dominant clique. It was formed to contradict and destroy an oppressive imperialism: it can only thrive by the free co-operation of the partners, finding their proper end in a prosperity shared by all. Such is a short summary of some of the leading topics treated here, those perhaps in which public interest has been most keenly aroused. But nothing has been said in this introduction of Art or Music, and of Religion only a little by implication. It may be well in conclusion to attempt a still more summary impression of the main drift of the period on the spiritual side. We may in such a wider view see some common tendency in all these activities, some inspiration of religion, some link with art, some impulse to live strongly and to hope. The present writer would find this leading thread in the increasing stress laid by recent European thought on the spiritual, or psychological, side of every problem, in the growing desire to understand the character of man's own nature and to develop all the powers of his soul.