ion in this falling off in the birth
rate is probable. It is rendered necessary by the fall in the death
rate and possible by the fact that birth has ceased to be a mere
physiological accident {184} and is coming under human control. "The
most important factor in the change," says Dr. John Shaw Billings, "is
the deliberate and voluntary avoidance or prevention of child-bearing
on the part of a steadily increasing number of married people who
prefer to have but few children."[19] The spreading of the knowledge
of birth control and the increasing financial burden of children in an
urbanised society composed of economically ambitious people will
probably prevent our population from ever again increasing as rapidly
as it did half a century ago.[20]

In the meanwhile our immigration (until the outbreak of the present
war) continued to increase. In the ten years ending June 30, 1914,
over ten million immigrant aliens arrived in the United States, of whom
approximately seven millions remained. Nor has the high point in
immigration been surely attained. The European population increases so
rapidly that the excess of births over deaths is between three and four
times the entire emigration. Immigration tends to flow from countries
where the pressure of population is greater to countries like the
United States, where the pressure is less. Unless there is restriction
we may witness within the next decades a new vast increase in
immigration, which will result in a rapid growth of our population and
a resulting pressure upon our agricultural (and other natural)
resources, that will vastly increase the intensity and bitterness of
our {185} competition for the world's markets and the world's
investment opportunities.

By thus increasing our agricultural product, and developing our home
market and our less directly competitive industries and by slackening
an increase in our population, which would otherwise force us into
foreign adventures, we tend to approach a balanced economic system and
a parallel growth of extractive and manufacturing industries. Such a
dependence in the main on home resources for the nation's primal needs
is in the circumstances the best preventive of an imperialistic policy
that might lead to war. But there is an even closer-lying incentive to
imperialism and war. A nation may have a sufficiently wide base and an
efficient industrial development but because of internal economic
mal-adjustments may be