How much the natural limitations of man will permit him to learn and understand; how far his instincts and emotional nature would allow him to be controlled by knowledge, if he had it; what would be the results to life if reason could control him, are pertinent questions that affect all discussion and which may never be satisfactorily answered. It is entirely possible that the student who tries to point out better ways and teach better methods does it only to satisfy his own emotions and is often conscious that it does nothing else. But, whatever the inducing cause or result, given a brain and nervous system and the material that civilization furnishes for reflection, these and other important subjects will be interesting topics of study and furnish material for the reflective powers of man. XXIX WAR AND CRIME 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.