 The way things get better, the way an economy grows, the way people get richer, is that someone comes up with a better way to do something, a way that takes a little less work. Over time, there are small improvements in life and in light. The Romans figure out how to make a lamp that's a little more efficient. People start to use whale oil. This, of course, is very, very bad for whales, but whales have a lot of fat. They were like these big swimming sources of fuel.