Those who are supposed to be fed with the spontaneous fruits of the earth, cannot, from what has been said, multiply beyond that proportion; at the same time the generative faculty will work its natural effects in augmenting numbers. The consequence will be, that certain individuals must become worse fed, consequently weaker; consequently, if in that weakly state, nature should withold a part of her usual plenty, the whole multitude will be affected by it; a disease may take place, and sweep off a far greater number than that proportioned to the deficiency of the season. What results from this? That those who have escaped, finding food more plentiful, become vigorous and strong; generation gives life to additional numbers, food preserves it, until they rise up to the former standard.
Thus the generative faculty resembles a spring loaded with a weight, which always exerts itself in proportion to the diminution of resistance: when food has remained some time without augmentation or diminution, generation will carry numbers as high as possible; if then food come to be diminished, the spring is overpowered; the force of it becomes less than nothing. Inhabitants will diminish, at least, in proportion to the overcharge. If upon the other hand, food be increased, the spring which stood at 0, will begin to exert itself in proportion as the resistance diminishes; people will begin to be better fed; they will multiply, and in proportion as they increase in numbers, the food will become scarce again.
I must here subjoin a remark very analogous to this subject. That the generative faculty in man (which we have compared to a spring) and the care and love we have for our children, first prompt us to multiply, and then engage us to divide what we have with our little ones. Thus from dividing and subdividing it happens, that in every country where food is limited to a certain quantity, the inhabitants must be subsisted in a regular progression, descending down from plenty and ample subsistence, to the last periods of want, and even sometimes starving for hunger.
Although the examples of this last extremity are not common in some countries, yet I believe they are more so than is generally imagined; and the other stages of want are productive of many diseases, and of a decay which extinguishes the faculty of generation, or which weakens it, so as to produce children less vigorous and less healthy. I appeal to experience, if this reasoning be not just.
Put two or three pairs of rabbits into a field proper for them, the multiplication will be rapid; and in a few years the warren will be stocked: you may take yearly from it a hundred pairs, I shall suppose, and keep your warren in good order: give over taking any for some years, you will perhaps find your original stock rather diminished than increased, for the reasons above mentioned. Africa yearly furnishes many thousands for the cultivation of America; in this she resembles the warren. I have little doubt but that if all her sons were returned to her, by far the greater part would die of hunger.
CHAP. IV.
Continuation of the same Subject, with regard to the natural and immediate effects of Agriculture, as to Population.
I proceed in my examination. I now suppose man to add his labour and industry to the natural activity of the soil: in so far, as by this he produces an additional quantity of food, in so far he lays a foundation for the maintenance of an additional number. This number I shall call (B). From this I conclude, that as (A) is in a constant proportion to the spontaneous fruits, so (B) must be in proportion to agriculture (by this term I understand at present every method of augmenting food by labour) consequently the number maintained by the labour of mankind must be to the whole number of mankind as (B) is to (A + B), or as (B) is to (A) and (B) jointly.
By this operation we find mankind immediately divided into two classes; those who, without working, live upon the spontaneous fruits of the earth; that is, upon milk, cattle, hunting, &c. The other part, those who are obliged to labour the soil. It is proper next to inquire what should naturally oblige a man to labour; and what are the natural consequences of it as to multiplication.
We have already said, that the principle of generation is inherent in man, and prompts him to multiply. Another principle, as naturally inherent in the mind, as the first is in the body, is self-love, or a desire of ease and happiness, which prompts those who find in themselves any superiority; whether personal, or political, to make use of every natural advantage. Consequently, such will multiply proportionably: because by appropriating to themselves the fruits of the earth, they have the means of subsisting their offspring. The others, I think, will very naturally become their servants; as this method is of all others the most easy to procure subsistence. This is so analogous to the nature of man, that we see every where, even among children, that the smallest superiority in any one over the rest, constantly draws along with it a tribute of service in one way or other. Those who become servants for the sake of food, will soon become slaves: for slavery is but the abuse of service, established by a civil institution; and men who find no possibility of subsisting otherwise, will be obliged to serve upon the conditions prescribed to them.