The economic theory of war comes to its own in the view that industry now controls the world, that industry is the power behind politics, and that industrial needs are the real energies that make wars. We live in an industrial age, they say, and industry rules. Plainly to find the whole truth about this relation of industry to war is no simple matter. There are at least three more or less separate questions involved in it. We need to know whether an industrial state of society, or the industrial stage of economic development, is especially prone to cause wars, as distinguished from more general political and economic interests. We need to know whether wars, in an industrial stage, do really serve either the interests of industry or countries as a whole. Finally, there is the question whether those who control industry and finance do actually create wars. In the industrial and financial stages of economic development new conditions arise which certainly must be taken into account in any theory of war. There are deep changes in national life. The moods of the city become a new force or a new factor in national life. Socialistic ideas and new aspects of nationalism and patriotism appear. There is a spirit of unrest; both pessimistic and optimistic tendencies in society are increased; the motive of power takes new forms, and there is a deep stirring of fundamental feelings and impulses. The crowd instincts, the old hunger motives, are felt beneath the surface of life. This is the effect of industrialism upon the psychic forces of peoples in their collective aspects. Nations also become as wholes more specialized in the industrial life; they are dependent upon one another as never before. All the ancient motives of commerce are stimulated, and the minds of nations revert to the old fears and the old romance connected with the thought of the seas. The growing interdependence of nations produces a peculiar and paradoxical condition. Competition in regard to markets arises, with all the complications and strains that we have seen in recent years. There are new motives of aggression, but at the same time the need and motives for peace are increased. Industries in general thrive best in an era of assured peace. They live upon the wealth and prosperity they themselves create. Intrigue, not force, is their proper weapon. Le Bon (42) says, that the desire to create markets was not the cause of the great war, because expansion went on very well in the time of peace. Germany had no aggressive designs except commercial designs we are told. Mach (95) tells us Germany's whole future, the success of her carefully laid plans for industrial development and supremacy, depended upon continued peace.