In this respect history is neither better nor worse than the latest explanation of the origin and order of the world of organised matter. Here too we are landed in the final resort at what is neither more nor less than an accident. Natural selection, or the survival of the fittest in the universal struggle for existence, is now held by the most competent inquirers to be the principal method to which we owe the extinction, preservation, and distribution of organic forms on the earth. But the appearance both of the forms that conquer and of those that perish still remains a secret, and to science an accident and a secret are virtually and provisionally the same thing. In a word, there is an unknown element at the bottom of the varieties of creation, whether we agree to call that element a volition of a supernatural being, or an undiscovered set of facts in embryology. So in history the Roman or Italo-Hellenic empire, rising when it did, was the salvation of the West, and yet the appearance at the moment when anarchy threatened rapidly to dissolve the Roman state, of a man with the power of conceiving the best design for the new structure, seems to partake as much of the nature of chance, as the non-appearance of men with similar vision and power in equally momentous crises, earlier and later. The rise of a great constructive chief like Charlemagne in the eighth century can hardly be enough to persuade us that the occasion invariably brings the leader whom its conditions require, when we remember that as concerns their demands the conditions of the end of the eighth century were not radically different from those of the beginning of the sixth, yet that in the earlier epoch there arose no successor to continue the work of Theodoric. We have only to examine the origin and fundamental circumstances of the types of civilisation which rule western communities and guide their advance, to discern in those original circumstances a something inscrutable, a certain element of what is as though it were fortuitous. No science can as yet tell us how such a variation from previously existing creatures as man had its origin; nor, any more than this, can history explain the law by which the most striking variations in intellectual and spiritual quality within the human order have had their origin. The appearance of the one as of the other is a fact which cannot be further resolved. It is hard to think in imagination of the globe as unpeopled by man, or peopled, as it may at some remote day come to be, by beings of capacity superior enough to extinguish man. It is hard also to think of the scene which western Europe and all the vast space which the light of western Europe irradiates, might have offered at this moment, if nature or the unknown forces had not produced a Luther, a Calvin, or a Voltaire.