flow of population into other lands to grow food for themselves, or, failing this, it must produce at home an ever-growing surplus of manufactures which evade the law of decreasing returns and find markets for them, so as to obtain payment in food from foreign lands, which, in their turn, are thus forced more quickly to experience the pinch of the same natural law. As more nations pursue this course they either realise directly the pressure of the law driving them to find new lands for their surplus population, or they find themselves embroiled in an ever fiercer competition with rival manufacturing nations seeking a share in an over-stocked or too slowly expanding market for manufactures. Imperialism lies in both directions, and cannot be avoided. “The cause of war is as permanent as hunger itself, since both spring from the same source, the law of diminishing returns. So long as that persists, war must remain, in the last analysis, a national business undertaking, designed to procure or preserve foreign markets, that is, the means of continued growth and prosperity. ‘Chacun doit grandir ou mourir’.” [52]
Now the finality of this alleged necessity has often been subjected to incidental criticism, so far as Great Britain is concerned. Imperialism, it has been shown, is not in fact necessitated in order to obtain by trade an increased food supply which should keep pace with the growth of British population, nor has it chiefly been engaged in forwarding such trade; still less is it engaged in finding land upon which our surplus population may subsist and multiply.
But the validity of the whole argument from natural history is contestable. As man grows in civilisation, i.e. in the art of applying reason to the adjustment of his relations with his physical and social environment, he obtains a corresponding power to extricate himself from the necessity which dominates the lower animal world. He can avoid the necessity of war and expansion in two ways, by a progressive mitigation of the law of diminishing returns in agriculture and the