It is undeniable that population will increase prodigiously-just as it has increased prodigiously during the last few centuries, following upon the increase in food-getting efficiency. The magnitude of population in that future day is well nigh unthinkable. But there is only so much land and water on the surface of the earth. Man, despite his marvellous accomplishments, will never be able to increase the diameter of the planet. The old days of virgin continents will be gone. The habitable planet, from ice-cap to ice-cap, will be inhabited. And in the matter of food-getting, as in everything else, man is only finite. Undreamed-of efficiencies in food-getting may be achieved, but, soon or late, man will find himself face to face with Malthus’ grim law. Not only will population catch up with subsistence, but it will press against subsistence, and the pressure will be pitiless and savage. Somewhere in the future is a date when man will face, consciously, the bitter fact that there is not food enough for all of him to eat.
When this day comes, what then? Will there be a recrudescence of old obsolete war? In a saturated population life is always cheap, as it is cheap in China, in India, to-day. Will new human drifts take place, questing for room, carving earth-space out of crowded life. Will the Sword again sing:
“Follow, O follow, then,
Heroes, my harvesters!
Where the tall grain is ripe
Thrust in your sickles!
Stripped and adust
In a stubble of empire
Scything and binding
The full sheaves of sovereignty.”
Even if, as of old, man should wander hungrily, sword in hand, slaying and being slain, the relief would be only temporary. Even if one race alone should hew down the last survivor of all the other races, that one race, drifting the world around, would saturate the planet with its own life and again press against subsistence. And in that day, the death rate and the birth rate will have to balance. Men will have to die, or be prevented from being born. Undoubtedly a higher quality of life will obtain, and also a slowly decreasing fecundity. But this decrease will be so slow that the pressure against subsistence will remain. The control of progeny will be one of the most important problems of man and one of the most important functions of the state. Men will simply be not permitted to be born.
Disease, from time to time, will ease the pressure. Diseases are parasites, and it must not be forgotten that just as there are drifts in the world of man, so are there drifts in the world of micro-organisms—hunger-quests for food. Little is known of the micro-organic world, but that little is appalling; and no census of it will ever be taken, for there is the true, literal “abysmal fecundity.” Multitudinous as man is, all his totality of individuals is as nothing in comparison with the inconceivable vastness of numbers of the micro-organisms. In your body, or in mine, right now, are swarming more individual entities than there are human beings in the world to-day. It is to us an invisible world. We only guess its nearest confines. With our powerful microscopes and ultramicroscopes, enlarging diameters twenty thousand times, we catch but the slightest glimpses of that profundity of infinitesimal life.
Little is known of that world, save in a general way. We know that out of it arise diseases, new to us, that afflict and destroy man. We do not know whether these diseases are merely the drifts, in a fresh direction, of already-existing breeds of micro-organisms, or whether they are new, absolutely new, breeds themselves just spontaneously generated. The latter hypothesis is tenable, for we theorise that if spontaneous generation still occurs on the earth, it is far more likely to occur in the form of simple organisms than of complicated organisms.
Another thing we know, and that is that it is in crowded populations that new diseases arise. They have done so in the past. They do so to-day. And no matter how wise are our physicians and bacteriologists, no matter how successfully they cope with these invaders, new invaders continue to arise—new drifts of hungry life seeking to devour us. And so we are justified in believing that in the saturated populations of the future, when life is suffocating in the pressure against subsistence, that new, and ever new, hosts of destroying micro-organisms will continue to arise and fling themselves upon earth-crowded man to give him room. There may even be plagues of unprecedented ferocity that will depopulate great areas before the wit of man can overcome them. And this we know: that no matter how often these invisible hosts may be overcome by man’s becoming immune to them through a cruel and terrible selection, new hosts will ever arise of these micro-organisms that were in the world before he came and that will be here after he is gone.
After he is gone? Will he then some day be gone, and this planet know him no more? Is it thither that the human drift in all its totality is trending? God Himself is silent on this point, though some of His prophets have given us vivid representations of that last day when the earth shall pass into nothingness. Nor does science, despite its radium speculations and its attempted analyses of the ultimate nature of matter, give us any other word than that man will pass. So far as man’s knowledge goes, law is universal. Elements react under certain unchangeable conditions. One of these conditions is temperature. Whether it be in the test tube of the laboratory or the workshop of nature, all organic chemical reactions take place only within a restricted range of heat. Man, the latest of the ephemera, is pitifully a creature of temperature, strutting his brief day on the thermometer. Behind him is a past wherein it was too warm for him to exist. Ahead of him is a future wherein it will be too cold for him to exist. He cannot adjust himself to that future, because he cannot alter universal law, because he cannot alter his own construction nor the molecules that compose him.
It would be well to ponder these lines of Herbert Spencer’s which follow, and which embody, possibly, the wildest vision the scientific mind has ever achieved:
“Motion as well as Matter being fixed in quantity, it would seem that the change in the distribution of Matter which Motion effects, coming to a limit in whichever direction it is carried, the indestructible Motion thereupon necessitates a reverse distribution. Apparently, the universally-co-existent forces of attraction and repulsion, which, as we have seen, necessitate rhythm in all minor changes throughout the Universe, also necessitate rhythm in the totality of its changes—produce now an immeasurable period during which the attractive forces predominating, cause universal concentration, and then an immeasurable period during which the repulsive forces predominating, cause universal diffusion—alternate eras of Evolution and Dissolution. And thus there is suggested the conception of a past during which there have been successive Evolutions analogous to that which is now going on; a future during which successive other Evolutions may go on—ever the same in principle but never the same in concrete result.”