And of late years the Malthusian theory has received new support in the rapid change of ideas as to the origin of man and the genesis of species. That Buckle was right in saying that the promulgation of the Malthusian theory marked an epoch in the history of speculative thought could, it seems to me, be easily shown; yet to trace its influence in the higher domains of philosophy, of which Buckle’s own work is an example, would, though extremely interesting, carry us beyond the scope of this investigation. But how much be reflex and how much original, the support which is given to the Malthusian theory by the new philosophy of development, now rapidly spreading in every direction, must be noted in any estimate of the sources from which this theory derives its present strength. As in political economy, the support received from the doctrine of wages and the doctrine of rent combined to raise the Malthusian theory to the rank of a central truth, so the extension of similar ideas to the development of life in all its forms has the effect of giving it a still higher and more impregnable position. Agassiz, who, to the day of his death, was a strenuous opponent of the new philosophy, spoke of Darwinism as “Malthus all over,”[16] and Darwin himself says the struggle for existence “is the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms.”[17] It does not, however, seem to me exactly correct to say that the theory of development by natural selection or survival of the fittest is extended Malthusianism, for the doctrine of Malthus did not originally and does not necessarily involve the idea of progression. But this was soon added to it. McCulloch[18] attributes to the “principle of increase” social improvement and the progress of the arts, and declares that the poverty that it engenders acts as a powerful stimulus to the development of industry, the extension of science and the accumulation of wealth by the upper and middle classes, without which stimulus society would quickly sink into apathy and decay. What is this but the recognition in regard to human society of the developing effects of the “struggle for existence” and “survival of the fittest,” which we are now told on the authority of natural science have been the means which Nature has employed to bring forth all the infinitely diversified and wonderfully adapted forms which the teeming life of the globe assumes? What is it but the recognition of the force, which, seemingly cruel and remorseless, has yet in the course of unnumbered ages developed the higher from the lower type, differentiated the man and the monkey, and made the Nineteenth Century succeed the age of stone?