"Wherein does a good system of agriculture consist? In the first place, in thorough plowing; in the second place, in thorough plowing; and, in the third place, in manuring." Varro, who lived at the same time as Cato, wrote as follows: "The land must rest every second year, or be sown with lighter kinds of seeds, which prove less exhausting to the soil. A field is not sown entirely for the crop which is to be obtained the same year, but partly for the effect to be produced in the following; because there are many plants which, when cut down and left on the land, improve the soil. Thus lupines, for instance, are plowed into a poor soil in lieu of manure. Horse manure is about the best suited for meadow land, and so in general is that of beasts of burden fed on barley; for manure made from this cereal makes the grass grow luxuriantly." Virgil wrote in his _Georgics:_ "Still will the seeds, tho chosen with toilsome pains, Degenerate, if man's industrious hand Cull not each year the largest and the best." It was in 1859 that Baron von Liebig wrote as follows, regarding these and similar _ancient _teachings: "All these rules had, as history tells us, only a temporary effect; they hastened the decay of Roman agriculture; and the farmer ultimately found that he had exhausted all his expedients to keep his fields fruitful and reap remunerative crops from them. Even in Columella's time, the produce of the land was only fourfold. It is not the land itself that constitutes the farmer's wealth, but it is in the constituents of the soil, which serve for the nutrition of plants, that this wealth truly consists." Suppose, Mr. Hill, that a successful American farmer should tell you that your bank account will actually increase if you will give from three to five members of your family the privilege of writing checks instead of following the single checking system. "But," you will ask, "doesn't rotation produce a larger aggregate yield of crops than the single crop system?" Certainly, and, likewise, a rotation of the check book will produce a larger aggregate of the checks written; but the ultimate effect on the bank deposit is the same as on the natural deposit of plant food in the soil, and finally the checks will not be honored. Indeed, it would be a fine sort of perpetual motion if we could actually enrich the soil by the simple rotation of crops, and thus make something out of nothing.