108 THE SHADOW OF THE WORLD’S FUTURE 
controls and operated in foreign interests; and diver- 
sities of aspiration when people are not of one race and 
language; these, in the existing state of things, greatly 
intensify the difficulty of those movements of popula- 
tion, which are necessary to minimise the troubles 
coming from undue local increases of numbers. All 
these matters bear upon the question as to how the 
principles, enunciated by Malthus, can act upon the 
modern world. They forcefully remind us that “ New 
Malthusianism ” has to take account of the type of 
difficulties now existing or arising. It has also to 
envisage the possible elements in the reconstruction of 
human affairs. For example, when the peoples of 
over-populated countries decide against birth-control, 
other peoples have to take into account whether the 
former propose to force the migration question in any 
way. One of the immediate difficulties, sometimes, is 
to decide as to whether such decisions are merely 
official or are national. In the latter case they may 
mean conflict, which, in the circumstances, may be 
unavoidable. One sees that Malthusianism, as soon as 
it takes practical account of world-facts, has become 
a thing of immense moment. 
Another important aspect of the migration-issue is 
this: if a territory be appreciably relieved by the 
emigration of its inhabitants, the condition before 
relief tends to re-establish itself. In other words, the 
habitual social and economic pressure, due to the 
excess of the effective reproductive impulse over the 
normal density conditions, is almost certain to renew 
itself whenever it is relieved. Thus, other things be- 
ing equal, constructive birth-controls will have to be 
permanent, though adapting themselves to fluctuat- 
ing population-conditions. Thus people with a high 
residual rate of natural increase (that is, a rate allowing 
for infantile and early mortality) challenge the occupa- 
tion of territory by other peoples. Such a fact directs