Shmittah and "The Tragedy of the Commons"

If a person puts more cattle into his own field, the amount of the subsistence which they consume is all deducted from that which was at the command of his original stock. ... [I]f, before, there was no more than a sufficiency of pasture, he reaps no benefit from the additional cattle, what is gained in one way being lost in another. But if he puts more cattle on a common, the food which they consume forms a deduction which is shared between all the cattle, as well that of others as his own, in proportion to their number, and only a small part of it is taken from his own cattle. In an inclosed pasture, there is a point of saturation... beyond which no prudent man will add to his stock. In a common, also, there is in like manner a point of saturation. But the position of the point in the two cases is obviously different.
William Forster Lloyd, Two Lectures on the Checks to Population (1833)

Therein is the tragedy. Each man is locked into a system that compels him to increase his herd without limit – in a world that is limited. Ruin is the destination toward which all men rush, each pursuing his own best interest in a society that believes in the freedom of the commons.
Garrett Hardin, "The Tragedy of the Commons" (1968)