"[Everything, and not just] all human enterprise can tend toward diminishing returns and unsustainability, but some modes have far more long-term prospects than others and some are socially suicidal, even in the short term. Many civilizations, from the Sumerians to the Maya, have faltered when overinvestments in the scale and complexity of food production produced ruinous diminishing returns. On American farms in the early 1800s, the balance between calories expended and calories produced as [the] food was about even. This occurred as tools reached a high stage of refinement but before machines replaced human labor and traditional knowledge. It implies a distinction between tools and machines, between work done with tools and work done by machines. Production improved while entropy was kept to a minimum. Under the current industrial farming system, it takes sixteen calories of “input” to produce one calorie of grain, and seventy calories of input to produce one calorie of meat. A hundred years ago, just before the introduction of… fossil fuel-based technologies, more than 30 percent of the American population was engaged in farming. Now the figure is 1.6 percent. The issue is not moral, academic, or aesthetic. […] It’s a matter of those ratios being made possible only because cheap oil and automation made up for so much human labor. We did what we did in the twentieth century because we could. Of course, not all farm labor amounts to slavery or serfdom. Depending on how farming is organized, it can result in a very satisfactory way of life and rewarding social relations. Agriculture in the United States was organized very differently in Pennsylvania and South Carolina 150 years ago, and not simply because of climatic differences. Farmers had quickly become addicted to a new debt system of annual operation, mortgaging their farms to raise cash to pay for new machinery and fertilizer—literally betting the farm on a good crop. With prices chronically depressed, mortgages could not be paid off. Farm foreclosures soared in the mid-1920s. Another unanticipated consequence of mechanized farming was the destruction of [the] soil. The tractor and its implements were machines that no one had previously experienced before, and it was some time before farmers noticed the insidious effects of soil compaction, rutting, and erosion that occurred. This would combine a few years later with an extended drought to produce the additional hardship of the ."