show that, let human beings increase to the full extent of their reproductive power, the increase of population can never exceed subsistence? This is clear when it is remembered that though in the vegetable and animal kingdoms each species, by virtue of its reproductive power, naturally and necessarily presses against the conditions which limit its further increase, yet these conditions are nowhere fixed and final. No species reaches the ultimate limit of soil, water, air, and sunshine; but the actual limit of each is in the existence of other species, its rivals, its enemies, or its food. Thus the conditions which limit the existence of such of these species as afford him subsistence man can extend (in some cases his mere appearance will extend them), and thus the reproductive forces of the species which supply his wants, instead of wasting themselves against their former limit, start forward in his service at a pace which his powers of increase cannot rival. If he but shoot hawks, food-birds will increase; if he but trap foxes the wild rabbits will multiply; the bumble bee moves with the pioneer, and on the organic matter with which man's presence fills the rivers, fishes feed.
Even if any consideration of final causes be excluded; even if it be not permitted to suggest that the high and constant reproductive force in vegetables and animals has been ordered to enable them to subserve the uses of man, and that therefore the pressure of the lower forms of life against subsistence does not tend to show that it must likewise be so with man, "the roof and crown of things;" yet there still remains a distinction between man and all other forms of life that destroys the analogy. Of all living things, man is the only one who can give play to the reproductive forces more powerful than his own, which supply him with food. Beast, insect, bird, and fish take only what they find. Their increase is at the expense of their food, and when they have reached the existing limits of food, their food must increase before they can increase. But unlike that of any other living thing, the increase of man involves the increase of his food If bears instead of
