due to the working of these two factors.  At starting he was physically less strong than many other creatures, and if he fought with others of his own kind, other animal species did the same.  He was ahead of them by his reason, and reason acted, and must act, through the concert of thinking beings.  This concert is not merely, or even mainly, an attachment among those living at the same time to co-operate for some common end; it is with man a conscious sequence of one generation on another.  Sometimes the movement of adaptation is slower, sometimes quicker, but in every case the living are carrying on the work of the dead, and their co-operation in time as well as space is due to the working of the same qualities of attachment and reason, the social factors, by which at any moment a community of men is bound together.

Still looking at the matter a priori, it is clear that the vast community of mankind, though it has come more closely in contact in recent years over all the planet, yet acts, and must act, habitually and momentarily, through many smaller aggregates.  Of these the leading types are the family and the country or nation.  The former is not directly relevant to our inquiry, the latter plays a leading part in it.  The former is less dependent on external conditions of land-formation and the like, and is in consequence more universal, more purely human.  The latter has been shaped by geographical conditions, by racial qualities, by the apparent accidents of history.  Its relation to the larger units of human society raises the most difficult, fundamental and unavoidable questions.  To curb aggressive nationalism is the root-problem of the present war.  To reconcile permanently nationalism with humanity would be to establish the everlasting peace.

Western society, indeed the whole community of mankind, is built up of these smaller units, the family and the nation, with their various intermediate groupings, but the historical process has by no means conformed at all exactly to this logical order.  Society has not been made in orderly fashion by forming families and then combining families to make hundreds, and hundreds to make counties, and counties nations, and so on to the whole.  A German god might have done this, but the way of nature and history was less perfect.  The minor forms of human association have been taking shape, being altered and on the whole improved, throughout the process.  At one point, of high importance for our argument, a larger form of association was achieved before the necessary constituent elements were articulated.  This was the Greco-Roman world encircling the Mediterranean and completed in the Roman Empire of the second century A.D.  It was the nucleus from which the Western world of modern civilization has been developed; yet it was there, settled in its main outlines, before the national units which it required for internal harmony and cohesion had taken any definite shape.  It is to the difficulties of their growth and mutual adjustment that we owe most of the conflicts of modern history.