The fundamental principle of the multiplication of all animals, and consequently of man, is generation; the next is food: generation gives existence, food preserves it. Did the earth produce of itself the proper nourishment for man, with unlimited abundance, we should find no occasion to labour in order to procure it. Now in all countries found inhabited, as in those which have been found desolate, if the state of animals be inquired into, the number of them will be found in proportion to the quantity of food produced by the earth, _regularly throughout the year_, for their subsistence. I say, regularly throughout the year, because we perceive in those animals which produce in great abundance, such as all the feathered genus, that vast multitudes are destroyed in winter; they are brought forth with the fruits of the earth, and fall in proportion. This principle is so natural, that I think it can hardly be controverted. As to man, the earth does not spontaneously produce nourishment for him in any considerable degree. I allow that as some species of animals support life by devouring others, so may man; but it must be observed, that the species feeding must always be much inferior in number to the species fed upon. This is evident in reason and in fact. Were the earth therefore uncultivated, the numbers of mankind would not exceed the proportion of the spontaneous fruits which she offers for their immediate use, or for that of the animals which might be the proper nourishment of man. There is therefore a certain number of mankind which the earth would be able to maintain without any labour: allow me to call this quantity (A). Does it not, from this exposition of the matter, appear plain, that without labour (A) never can increase any more than animals, which do not work for themselves, can increase beyond the proportion of food provided for them by nature? Let it be however observed, that I do not pretend to limit (A) to a determined number. The seasons will no doubt influence the numbers of mankind, as we see they influence the plenty of other animals; but I say (A) will never increase beyond the fixed proportion above-mentioned. Having resolved one question with regard to multiplication, and shewn that numbers must become greater or smaller according to the productions of nature, I come to the second thing proposed to be treated of in the chapter: to wit, what will become of the generative faculty after it has produced the full proportion of (A), and what effects will afterwards follow.