All natural phenomena affect the activities of man. It has been repeatedly observed that the number of crimes of assault and murder increases in the summer months and fluctuates with extreme heat or a cooler temperature. The nervous system of man is responsive to all sorts of physical and psychological influences, and criminologists take these into account in considering crime, as doctors take them into account in treating disease. Man is influenced by substantially all the things that affect other structures and by many things that do not. His nervous system is more delicate, his emotional nature more complex, and his brain permits the handling of impressions in a way not possible to lower organisms.  
The effect of war has always been manifest in human conduct. Man acts largely from habit and custom; he does as others do, without reflection as to why he should do it or why others do it. War is a sudden, violent and spectacular destroyer of all established habits. In its conduct and preparation it has rules of its own which have no analogy in civil life. The battlefield is a reversion to the primitive; a reversion which man finds it easy to make, for it appeals to fundamental instincts which civilization holds in leash with great difficulty and never with entire success. War especially appeals to the young. Their desire for activity, their impatience with restraint, their love of the spectacular, their untrained emotions, all find a ready outlet in war. Even those who are too young to fight still read of it, talk of it, play at it to the exclusion of other games. War is a profound and rapid maker of mental attitudes and of complexes that are quick to develop and slow to pass away. Both the quick development and slow decay are probably due to the fact that war meets a decided response in the primitive nature of man.
 
Nearly all the newspapers of America are now calling attention to the increase of crime since the close of the Great War. It is a topic of pulpit and platform discussion. Wild appeals are made for convictions and extreme penalties. Governors and boards of pardon and parole are urged to refuse clemency to prisoners and are roundly condemned when they do their plain duty, even though they do it very reluctantly and tardily.
 
It is probably true that the close of the war has shown a large increase in criminality, especially in crimes of violence. This is true not only of America but of all European countries. In some of the most afflicted ones civil government for a time has virtually broken down. Both the great need for food and clothing and the overthrowing of conventions, customs and habits are responsible for the change. Here we perceive a notable example of the almost instantaneous disruption of established folk-ways.
 
For more than four years most of the western world did nothing but kill. The whole world talked of slaughter and devoted its energy to killing. Every sentiment of humanity was forgotten. Even religious ties and religious commands were ignored. The prayers to the Almighty contained requests that He help the various fighting nations to kill their enemies. Everyone was taught to hate. The leaders in the war knew that boys could not do efficient killing unless they learned to fear and hate. The most outrageous falsehoods were freely circulated by every nation about its enemies and their conduct of the war. The highest rewards were offered for new and more efficient ways to kill. Every school was turned over to hate and preparation for war, and, of course, all the churches joined in the universal craze. God would not only forgive killing but reward those who were the most expert at the game.
 
The newspapers carried stories of battles every day, the dead and wounded often running into the tens of thousands. None of the reports was exact. Nothing was true. Everything was wild and exaggerated. Facts were not strong enough to make an impression. Lies were deliberately circulated to help the cause.
 
Every tradition and habit of life was broken and broken all the time. The commandment, "Thou shalt not kill," was repealed. Property was not only ruthlessly destroyed but openly confiscated. Lying was a fine art. When this bears a harvest after the war, the public loudly clamors for hanging boys whose psychology is a direct result of long and intensive training by the leaders of the world.
 
One life is not worth considering in the face of the holocaust that has taken its hundreds of thousands and has been defended in the schools and churches. It is not strange that the after-war harvest of crimes should come largely from boys, often those boys who did their part on the field of battle. Whether they got the psychology from killing or reading or hearing or playing soldier or training makes no difference. Everyone who has any reasoning power knows that they got it, that it was deliberately given to them if not forced upon them, and that just as deliberately the state is killing them because they took it.
 
It is not alone the young who show this psychology of killing that has grown out of the war. Organized society, the public, juries, judges,............