A clear explanation of the science of the most radical transformation of agriculture in 10,000 years. The "green" revolution in agriculture that began to unfold fifty years ago, has simply postponed the inevitable. A century ago it was estimated that a typical farmer expended 1 calorie of energy to produce one calorie of food. With the advent of the oil age, and the introduction of mechanized farming, pesticides and herbicides, the average 1 calorie of food production now requires 10 calories of energy input. Is agriculture, and humanity, prepared for the withdrawal of oil from the food cycle?