For most of recorded history, energy meant biomass — wood for heat and smelting, water and wind for milling, animals and humans for muscle. Wealth meant land, because land grew the fuel and fed the workers. The first energy crisis in the Western world was a wood crisis: by the early 1600s, England had cut down so much of its forest for shipbuilding, charcoal, and heating that the kingdom was running short of trees. The cure forced upon them — burning the black rocks dug out of mines for warmth — would, within two centuries, rewrite the global ranking of nations.