There are wave motions in fluids wherein each particle describes a tiny movement and then returns to its original place, the wave spreading widely. So, in population, a commotion at one spot is spread by wave motion throughout the whole mass, and the further from the center the less effect. A crime of a negro in Mississippi produces a commotion resulting in a lynching, but in New England this wave is not felt at all, as they are too far away. They only note an after-wave caused by the second crime. Popular excitements increase the movements of populations and are analogous to rise of temperature, indeed, it seems as though they boil and exert increased pressure. The "mob mind,"* is the motion in an excited mass. It closely resembles the action of all gregarious animals, for a tiny disturbance is transmitted to the herd, which takes instant flight - a habit due to natural selection.

War is merely a whole nation in movement like a boiling fluid, for some cause is acting on each particle. It always has the "will" of the nation behind it, in spite of the fact that many if not most of the units do not understand what is impelling them to form that "will." Leaders only lead, they never drive, and indeed statesmen often find that they cannot prevent war even when they know it will be disastrous. It is a flood. Now, when an ocean moves, as in the tides, the force causing it is tremendous, and similarly the force causing war is the irresistible struggle for existence among nations. Evolution depends upon these contests. Isolated populations are like dead seas, but unconfined warlike ones are clear rivers carrying on civilization. It seems as though war actually purifies nations, in the same way that agitation clarifies water by mixing oxygen to consume the filth. It certainly stirs up the filth temporarily, and makes it more evident and, like a muddy river, may even accumulate more, but that should not blind us to the fact that it has been a natural phenomenon whose benefits have outweighed its disadvantages. It will subsequently be explained how the warrior nations themselves are ending war because they are attaining its purposes in other ways; we are here concerned merely with its origin and fluid-like nature.

National diseases due to peace, are far worse than those due to war. War is hell because its destruction is more evident, but the destruction of peace is immeasurably more infernal, as we will shortly see. Our late war did not destroy nearly as many lives as Philadelphia destroys in a short period by typhoid fever. We often hear of the number of Filipinos killed in their war, but the number is inconsiderable compared with the quarter million or more killed by cholera after that war ended. The deaths in war are not a particle more ruthless than the deaths in peace in the lower classes from sheer inability to secure a living.

*See Prof. E. A. Ross, Popular Science Monthly, July, 1897.

Present Crisis In Population Movements

At the present time, and since 1896, we are in one of those frequent periodical crises of great excitement and movement in more than one part of the world. The average man cannot resist these wave motions and currents any more than a particle of water can resist the ocean currents. He is a particle in a fluid and an obedient subject of the laws under which he worked out his own evolution as a unit in society, and he instinctively obeys the laws governing the mass. He may think he is a free agent and that his conduct is the result of his own reasoning. What a man thinks is to such a large extent the result of his inheritance that we know that there is very little real logical reasoning on any topics even among civilized nations. In international affairs most men as particles of the mass are ruled by biological forces just as rigidly as the ocean particles are ruled by mechanical forces.

When the wind blows the seed of a tree broadcast, each seed obeys the forces acting on it, whether it is to survive or not, and when populations thus spread, each man obeys the forces acting on him whether he is to survive or not. It is not fate nor destiny. This nation shows a tendency to spread to a climate so different from the native one that extinction is positively certain. It behooves us to pause and see whether our impulse is as fatal as that which carries a moth to the flame.

In true representative countries, the representatives obey the popular will, and as a rule such nations are more quickly influenced by natural law than those with hereditary rulers. To be sure men are easily led, like sheep, and are intensely sensitive to suggestion, absorbing ideas which they subsequently think are their own. In race wars and expansion - they are far more under natural law than suggestion - nevertheless they can be guided by leaders even if they cannot be restrained, just as waters may be guided when we cannot confine them. It is the part of wisdom, then, to teach what leads to survival, and not obey the popular will leading to destruction.

By keeping in mind the fact that populations obey the laws of fluids in a general way, we can appreciate the result - wherever it is possible for this fluid to spread, it instantly does so. It is under constant internal pressure forcing it in every direction. A dam does not prevent water reaching the ocean to which gravity draws it, and immigration laws may temporarily check human currents, but the ultimate result is not changed in the slightest.