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.

So the historian accepts his limitations as the rules of the game, and sets out to see unity askance.  It is his rare chance, if events shift him, and set him gazing at a world in which, as now, half his own career is inside the picture; not perhaps very easy to find in a moment—­as one might fail to recognize oneself in a group-photograph—­but none the less there, and intelligible only in relation to its actual surroundings.

Looking back, indeed, over the course of anthropology and prehistoric archaeology, much of which lies in the years since 1870, and nearly all of it since 1815, the first thing which strikes us now is the frequency and delicacy of its response to contemporary thoughts and aspirations.  A few of the greatest men have recognized this at the time.  I quote from Karl Ernst von Baer, the founder of comparative embryology, and in great matters the master of men as different as Huxley, Spencer, and Francis Balfour.  He died in 1876, when political anthropology was still young; but in his great book on Man he ’appeals to the