Thus, I do not think it is possible to dispute the following proposition: the existence of any man, or of any number of men, whether organised into a polity or not, depends on the production of foodstuffs (that is, vital capital) readily accessible to man, either directly or indirectly, by plants. But it follows that the number of men who can exist, say for one year, on any given area of land, taken by itself, depends upon the quantity of food-stuffs produced by such plants growing on the area in one year. If a is that quantity, and b the minimum of food-stuffs required for each man, A/B=N, the maximum number of men who can exist on the area. Now the amount of production (a) is limited by the extent of area occupied; by the quantity of sunshine which falls upon the area; by the range and distribution of temperature; by the force of the winds; by the supply of water; by the composition and the physical characters of the soil; by animal and vegetable competitors and destroyers. The labour of man neither does, nor can, produce vital capital; all that it can do is to modify, favourably or unfavourably, the conditions of its production. The most important of these-- [161] namely, sunshine, range of daily and nightly temperature, wind--are practically out of men's reach.* On the other hand, the supply of water, the physical and chemical qualities of the soil, and the influences of competitors and destroyers, can often, though by no means always, be largely affected by labour and skill. And there is no harm in calling the effect of such labour "production," if it is clearly understood that "production" in this sense is a very different thing from the "production" of food-stuffs by a plant. * I do not forget electric lighting, greenhouses and hothouses, and the various modes of affording shelter against violent winds: but in regard to production of food-stuffs on the large scale they may be neglected. Even if synthetic chemistry should effect the construction of proteids, the Laboratory will hardly enter into competition with the Farm within any time which the present generation need trouble itself about.