equilibrium of physical forces and like analogies, instead of squaring their theories with the facts. This gives Professor Carver his chance to question the sanity of those who reject his favorite doctrines.
At first thought, scientists may favor a settlement of economic problems by the use of familiar ideas involving no economic knowledge, but in the end it will prove a mistake to appeal from adverse economic opinion to those versed in physical science. The orthodox economists were city people who let their imagination have free play in agriculture. One of their pictures was that of a vast plain of identical soil and climate. After picturing this world, they asked what motive can any one have to move from one part to another? To this Professor Carver replies, "whenever agricultural populations tend to spread, it is either a sign of insanity on their part or of diminishing returns on land."
To deny this, an economist does not have to pump water up hill. He questions the picture on which the law of diminishing returns is based. The principal that Professor Carver overlooks is the localization of soils, climates and products. The various geological deposits are irregularly placed and the climates found in different localities are even more diverse. Animal and plant life have been localized so that each locality yields different products or the same product at varying costs. No acre can yield as much return to labor as if it were spent on many acres or in many localities. Conversely, no race living on one article of food or using one kind of clothing or shelter can be as vigorous as those who supply themselves with a greater variety. The spread of population is due to this fact. The more climates, soils, animals and plants utilized, the better the living and the lower the costs.
A primitive community does not, as Professor Carver assumes, use a single soil and some one food. It is as complex as a modern state. The bottom land is used for plowing, the upland for grazing. There are wood lots, fishing places and an open region where wild game roams. Men go farther for goods in the modern than in a primitive world, but this does not imply diminishing return. When they herded sheep in an adjacent mountain valley, the effort then needed to get a pound of wool was greater than it now is to bring it from Australia. We have increased the distance traveled, but we have reduced the cost. Every spread of population has brought increasing returns because it has helped men to utilize the natural resources of the various localities. Is a community wise or foolish which uses different soils and climates instead of confining itself to one? Can two communities with different soils and climates exchange commodities to mutual advantage? If they can, there is a valid reason for the spread of population. Such a movement is not as insane as it seems to those who do not appreciate the localization of resources.
Professor Carver asks why England should not get all her agricul-