 but they did. I ran into a woman at Yale, and she, believe it or not, it's just unbelievable, actually. She actually had wage data and price data from the Babylonian era, so 4,000 years ago. So now he has these numbers, but he needs to know one other thing. How much light are people getting for their money? In ancient Babylon, people used lamps for light, so Nordhaus decided to make one.