This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
David Ricardo was trying to explain something that troubled him about early nineteenth-century Britain: why did landowners keep getting richer as the country as a whole grew more prosperous? His 1817 answer, laid out in On the Principles of Political Economy and Taxation, rested on a simple physical fact about farmland. As a growing population demands more food, farmers must extend cultivation onto progressively less fertile land, land that yields less output for the same labor and capital. The most fertile land, farmed first, now produces more than it costs to work, and that surplus above cost is rent, paid to whoever owns the good land, not earned by anyone's effort. Ricardo generalized the underlying mechanism, that successive equal additions of a variable input to a fixed input eventually yield smaller and smaller returns, into what economists now call the law of diminishing marginal returns, and it now explains far more than farmland: why a factory adding workers to one fixed assembly line eventually gains less from each additional hire, why a firm's short-run marginal cost curve turns upward, and why simply throwing more of one input at a fixed problem is rarely a free path to unlimited output.