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