We could not, indeed, be sure that if every one in Western Europe were a trained scientist, wars would cease from the earth: certain professors have taught us too well for that. But in so far as men come to recognize that the great body of organized knowledge is a common possession, due to the united efforts of different nations, and that it can only be increased by joint action and may be increased to such a point that the whole of life is a happier and nobler thing, so far they will be averse to war. And in its various applications, to increasing production and quickening communication, to lengthening life and healing sickness, to protecting workers and cheapening food, men see the natural fruits of an activity whose basis is common thought and its ultimate purpose the common good. It has been said with truth that it is easier to trace the growth of science as a joint product of co-operating minds, than to find a growth of common sentiments among the men and the nations who have created it. True among individuals, it must be at least as true among groups and nations. We may work successfully with some one at a problem or learn from a teacher or a companion when we dislike him personally and do not seek his society apart from the needs of our common work. It has often happened, and will happen again in private and public. But though particular antipathies may increase, the tendency to dislike others is a diminishing quality among civilized men. In the long run common sense and necessity will prevail. We are born to live a while before we die; and we must live on the same planet, sometimes next door to those who have sworn a never-dying hate. II UNITY IN PREHISTORIC TIMES[1] The new perspective, with all its shift of values, which is forced on us by the war, touches the past no less than the present and the future. However objectively we try to present to ourselves the data of history, we cannot emancipate ourselves from the need to present them from a point of view which must in the last resort be our own. We may bring ourselves by training and criticism nearer to the centre of things, more intimate with essential factors and remote from the trivial periphery; but it is a matter of degree, and historical study an affair after all of mental triangulation. Like a surveyor in the field, we are safest in our determination of any third position if we have already knowledge of two, and of how the third looks from both of them. And even if we were indeed at the centre of things, I suppose we might take our round of angles quite uselessly, unless we had also some divine gift of judging distances.