If a number of men live on the banks of a stream which offers a supply of water far in excess of all their requirements, no question of water-supply rises among them. If, however, they need water to irrigate their land, or if they keep flocks and herds which must get water from few, scattered, and scanty springs, water may come to be an object of earnest contention and struggle; if they want water for power, they find that the power of a certain fall is a limited quantity. If they contend for it they may divide it up. If the competitors become more numerous, an advancing limitation and deficiency are experienced by all; they run inevitably into a situation where so many want all that none have any. If they want air for power, they find that the favorable situations for windmills are limited, that these will all be occupied as the number who need them increases, and then that the occupiers will impede each other.
If men who have a large wood-supply waste it as fuel, no human interest is affected. It is true even then that what one takes out of the supply of nature another cannot have and use; but when there is more than enough for all, no protest is made. As numbers increase and the wood is cut off, every man who appropriates a tree to make a table out of it, or to burn it for his own fuel-supply, invades by just so much the sphere of interest of his neighbors, and as the number increases all must sink into a condition of want and misery, that is, of imperfectly satisfied necessities, not in a direct ratio, but under the same advancing progression.
If the woods are full of game and the men are few, there is no problem of food supply and no social question. Land means nothing but game. Any one who kills an animal invades and exhausts the common stock,
