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.