46 THE SHADOW OF THE WORLD’S FUTURE
resources which our increasing knowledge and power
have placed at our disposal. It is only too easy to
make the advantages, which accrue through a more
sensible use of our earth’s surface, disappear. Thus
comparing the different standards-of-living which are
characteristic of the various peoples of the earth at
the present time, we see that there is no fixed limit to
human desire for luxury. If, then, we consider the
further possible expansion of the spirit of luxuriousness,
we recognise that there is no unique solution to the
problem before us. For there is no intrinsic limit to
human desires, and the luxury of to-day tends to
become the penury of to-morrow.
It is because of this that the population-problem is
not merely a mathematico-physical one. It involves
our whole conception of life. Our social and our
ethical traditions are real factors in the adjustment
of communities to world-conditions. The evidence of
this may be seen in a nation’s consideration, for example,
of what may reasonably be expected by its citizens in
respect of the standard-of-living to which it deems
them to be entitled. Thus it immediately affects the
solution of the migration question. One nation has
experts who solve its population-possibilities on the
assumption that its existing mode of living is to
continue, whatever may happen elsewhere. Another
people object to the rapid influx of others because
it affects the non-economic rate, judged by worldstandards,
 at which, for example, even unskilled labour
is rewarded.
The significance of the acceleration of the rates of
production of the minerals and metals, before referred
to, the rate at which forests are being exploited for
timber wants and for paper, and indeed also that of
the mere rate of human increase, is readily seen by
considering the actual meaning of any such rates, in
a suitable way. The rate of increase of individual