“A Babylonian in 1750 BCE would have had to labor fifty hours to spend one hour reading his cuneiform tablets by a sesame-oil lamp. In 1800, an Englishman had to toil for six hours to burn a tallow candle for an hour. (Imagine planning your family budget around that—you might settle for darkness.) In 1880, you’d need to work fifteen minutes to burn a kerosene lamp for an hour; in 1950, eight seconds for the same hour from an incandescent bulb; and in 1994, a half-second for the same hour from a compact fluorescent bulb—a 43,000-fold leap in affordability in two centuries. And the progress wasn’t finished: Nordhaus published his article before LED bulbs flooded the market. Soon, cheap, solar-powered LED lamps will transform the lives of the more than one billion people without access to electricity, allowing them to read the news or do their homework without huddling around an oil drum filled with burning garbage.”