Malthus found in all life the constant tendency to increase beyond the nourishment available. In a given area, not even the utmost imaginable improvement in developing the resources of the soil can or could keep pace with the unchecked increase of population.[22] This applies alike to Great Britain and to the whole world. At bottom, then, the check to population--and this is true of microbes or men--is want of food, notwithstanding that this is never the immediate and obvious check except in cases of actual famine. There must therefore be a “struggle for existence,” and as Darwin and Wallace saw, it follows as a necessary truth that, to use Spencer's term, the fittest must survive. The question is whether we are to accept starvation as, at bottom, the factor controlling population (which, in any case, must be and is controlled) or whether we can substitute something better--as for instance, the moral self-control which Malthus recommended. The single precept of this much maligned thinker was “Do not marry till you have a fair prospect of supporting a family”--a fairly decent and respectable doctrine. In the words of Mr. Kirkup, “the greatest and highest moral result of his principle is that it clearly and emphatically teaches the responsibility of parentage, and it declares the sin of those who bring human beings into the world for whose physical, intellectual, and moral well-being no satisfactory provision is made.” Who, alas, will declare that even after a century and a decade this great lesson is yet learnt? It is to be added, first, that though improvement in agriculture is to be commended on every conceivable ground, and though it may in some degree relieve and postpone the difficulty, it is infinitely incapable of abolishing it. Nothing but necessity can check the prolificness of life. To this doctrine, however, there is, as we shall shortly see, a great excepting principle, unrecognised by Malthus, discovered by Herbert Spencer, and of vast and universal importance. Secondly, it is to be noted that emigration--a real remedy for over-population--is so only for a time. It cannot possibly abolish the problem--short of the development of interplanetary communication, if then; and the observer of contemporary politics must be well aware, as Germany, for instance, is well aware already, that its effectiveness as a practical remedy for over-population in some European countries is already being arrested by the invaded states.