The advance of constructive labor and the subsidence and disappearance of destructive warfare is a genuine line of progression. One sees much of protection and something of construction in the office of war, as the Roman bridges survived throughout Europe long after the legions which built them and crossed them for new conquests had passed out of mind. Also, in the rising tide of labor there is a large admixture of warfare, of the purely militant spirit which is sometimes so dominant that it throws the entire movement into confusion and leads the laborer to renounce his birthright; but nevertheless the desire for battle is becoming constantly more restricted in area. It still sways in regions where men of untamed blood are dwelling, and among men who, because they regard themselves as a superior race, imagine that they are free from the ordinary moral restraints; but its territory constantly grows smaller and its manifestations more guarded. Doubtless war will exist for many generations among semi-savage tribes, and it will also break out in those nations which may be roused and dominated by the unrestricted commercial spirit; but the ordinary life of man will go on without it, as it becomes transmitted into a desire for normal human relationship. It is difficult to predict at what moment the conviction that war is foolish or wasteful or unjustifiable may descend upon the earth, and it is also impossible to estimate among how many groups of people this conviction has already become established.