The crude oil and natural gas markets have a long colorful history. To understand them, one needs some economic theory. The dominant view, of a fixed mineral stock, implies that a unit produced today means one less in the future. As mankind approaches the limit, it must exert ever more effort per unit recovered. This concept is false, whether stated as common sense or as elegant theory. Under competition, the price results from endless struggle between depletion and increasing knowledge. But sellers may try to control the market in order to offer less and charge more. The political results may feed back upon market behavior. These factors-depletion, knowledge, monopoly, and politics-must be analyzed separately before being put together to capture a slice of a changing history.