History seems to show us that wars are less directly willed than we have sometimes supposed, and perhaps that there is a large element of chance in them as regards a given war at any time and in any place. War in general is inherent in, or is a natural effect of, the laws of development of nations. Wars as historical events are not completely describable in terms of these laws. It is the old contrast between the historical and the scientific explanation of things that appears here. Nations have deep and vague desires, we say. They want satisfaction of their honor; they crave a dramatic life, even military prestige and glory, but we do not often find war itself definitely willed. The desires of nations, we repeat, tend to be too fundamental to be specific. Their specific desires are indeed and for that reason likely to be contradictory. They desire both war and peace at the same time, and have interests that may be served by both. They live in indecision like individuals. Motives conflict. They hesitate, and doubt, and fear. They shrink from taking the plunge. It requires the sharp and clear event, the chance event, most often, to precipitate them into wars. It is always to-morrow that they are to wage wars. So wars do not usually occur by the rational plans and devices of any man or any historical sequences of men, we may believe, and it is a question whether wars are very often intended in a real sense by any one. Wars occur as crises in events. The strains that produce them are certainly inherent in the relations of nations at all times, and even in the motives of personal politics, but in general these relations as consciously governed relations are in the direction of seeking the greatest advantage with the least show of force. The conditions must all be present, both the match and the powder, before war can take place. There must be a condition of strain, having certain psychological features none of which can be missing, the condition being something complex and not readily analyzable, at any given time. In addition to these strains events must take place which, in all their appearances, are fortuitous.
One might argue from this that the cure of war consists in eternal watchfulness to see that the match does not touch the powder, that we must watch these events that precipitate wars and safeguard peoples from being affected by them. This, of course, is more or less the method of diplomacy; to some minds the league of nations is a device for doing this on a larger and more systematic scale. But when we study history and see what these war-causing incidents are, how numerous and how variable, we can see that diplomacy and statesmanship undertake an impossible task when they try to steer the world along its narrow historical course, with only historical landmarks for guides.