The progress or retrogression of the world depends, broadly speaking, upon the balance between acquisitiveness and rivalry. The former makes for progress, the latter for retrogression. When intelligence provides improved methods of production, these may be employed to increase the general share of goods, or to set apart more of the labour power of the community for the business of killing its rivals. Until 1914, acquisitiveness had prevailed, on the whole, since the fall of Napoleon; the past six years have seen a prevalence of the instinct of rivalry. Scientific intelligence makes it possible to indulge this instinct more fully than is possible for primitive peoples, since it sets free more men from the labour of producing necessaries. It is possible that scientific intelligence may, in time, reach the point when it will enable rivalry to exterminate the human race. This is the most hopeful method of bringing about an end of war.
For those who do not like this method, there is another: the study of scientific psychology and physiology. The physiological causes of emotions have begun to be known, through the studies of such men as Cannon (*Bodily Changes