Historians are liable to ante-date the completion of massive developments because of their preoccupation with origins. They are given to ante-dating the beginnings of massive developments for the same reason and also because such developments are rarely finally completed: when the end of one phase is usually but the preliminary to the onset of the next it is easy to mistake the onset of another phase for the beginning of an entirely new departure. These opposite hazards have affected our assessments of the origin and evolution of the modern states' system. Only when due allowance is made for the first can it be seen that a new European states' system emerged in the eighteenth century, and not at an earlier date. Only when careful regard is paid to the second can it be seen that, for all the twists and phases it has recently undergone, the system which then emerged or finally matured in Europe is the system which still holds the world in its framework. The present-day structure of world international relations is a structure between Great Powers, and it has come down in unbroken descent from the days when such a structure first materialised in Europe. It was during the eighteenth century that the actuality and the conception of a collection of Great Powers in Europe finally replaced an earlier framework of existing fact and inherited thought in which, while more than one state had always existed, it had been natural for one Power to be rated above the rest and impossible for that Power's pretensions―resisted though they had always been by other states―to stop short of the control and protection of Christendom.