That agriculture may become a science, it is indispensable that man always repay to the great bank from which he has drawn his food, the debt he thereby has contracted. The earth, as has been already said, gives nothing, but is ready to lend everything; and when the debts are punctually repaid, each successive loan is made on a larger scale; but when the debtor fails in punctuality, his credit declines, and the loans are gradually diminished, until at length he is turned out from house and home. No truth in the whole range of science is more readily susceptible of proof than that the community which limits itself to the exportation of raw produce must end by the exportation of men, and those men the slaves of nature, even when not actually bought and sold by their fellow men. ... With the growth of commerce, the necessity for moving commodities back, and forth steadily declines, with constant improvement in the machinery of transportation, and diminution in the risk of losses of the kind that are covered by insurance against dangers of the sea, or those of fire. The treasures of the earth then become developed, and stone and iron take the place of wood in all constructions, while the exchanges between the miner of coal and of iron--of the man who quarries the granite, and him who raises the food--rapidly increase in quantity, and diminish the necessity for resorting to the distant market. * * * * * =_Edmund Ruffin, 1793-1863._= From "An Essay on Calcarcous Manures." =_156._= IMPROVEMENT OF ACID SOILS.