The greatest power on Earth comes from above. El Sol runs our atmosphere. The Earth below us runs on geothermal power, fueled mainly by radioactive decay. This underground heat runs our tectonic plates, which make our landscapes. It also keeps Earth’s mantle warm enough to be ductile at long time scales, allowing less-dense continents to float above the more-dense oceanic crust, thereby differentiating land from sea. Between the solar power above and the geothermal power below is a world run by the cognitive power of human beings, who have engineered ways to tap the greater powers from above and below, everything from windmills to nuclear reactors.