Sir,--It is useless discussing the population question with Dr. Drysdale, because his letter is chiefly occupied with imputing to me things I never said, and then replying to them. I never denied "that population (now) tends (in some countries) to double in from twenty to thirty years," and I never said that "we need take no thought of the question of food supply"; and, further, Dr. Drysdale has no grounds for stating that I "do not know what Malthus has said," the fact being that I studied Malthus carefully more than thirty years ago, and was indebted to him for ideas which led me to a theory of the origin of species identical with that of Darwin. What I do say and maintain is, that the application of the principle of population to political economy is altogether erroneous, and that calculations founded on that principle are misleading. Herbert Spencer has shown, by a masterly survey of the whole realm of nature, that the greater proportionate development of the nervous system, which accompanies advancing civilization and a higher intelligence, is itself a cause of diminished fertility, of which Malthus knew nothing, but which will explain much that he misunderstood. As man becomes more intellectual and refined, as he leads a less animal and a more spiritual life, he will increase less and less rapidly, both from a diminished fertility and from a later period of marriage. The later period of marriage will arise from two causes. When the intellectual nature is more fully developed than the animal, the choice of a partner for life will become a matter of far higher importance, and will be conducted with far greater forethought and deliberation; while, at the same time, a man will hesitate to plunge into matrimony until he finds himself in a position to retain for himself and give to his future family those intellectual advantages which he values higher than mere animal enjoyments. Because the backwoodsmen and farmers of newly settled countries, leading an almost purely animal existence, double their numbers in twenty to thirty years, that is no measure whatever of the rate at which a community like ours will double itself when the influences which now act only on the upper stratum of society permeate the whole mass. The rate may go on diminishing so rapidly that the increased power of production may more than keep pace with it, and modern Malthusians have no right to assume the contrary without even an attempt at proof. The fact that, under slightly better social conditions, a very much denser population can be, and actually is, supported in far greater comfort than with us, is an indication of the true direction in which the working-classes should look to better their condition; and, in order that they may see how vitally the question of the "nationalization of the land" affects every one of them, I earnestly beg of them to read and re-read Mr. George’s book, "Progress and Poverty," and, having read it, to take action at the hustings to bring about a reform, which alone can raise them permanently to a higher level of comfort and general well-being.

Alfred R. Wallace.