Intuition tells us that the scarcity of space on the earth's surface should be closely tied both to population growth and to economic growth. Population growth should make land more scarce by raising the demand for food and private space and by raising the supply of labor, a factor of production that must cooperate with land. Intuition says that economic growth should tend to do the same, all things considered. The demand for food, a prime land-using product, would be expanded little by a rise in per capita incomes, but the rent on land should be bid up somewhat by the growth of other inputs into production, such as skills and man-made equipment. Intuition also suggests that land scarity should in turn retard the growth of population and per capita incomes. If space, privacy, and food are expensive, children should seem relatively costly. At the same time, higher space rents should mean slower economic growth than would be experienced if man could manufacture extra land cheaply.