John Green teaches you about railroads and some of the ways they changed the world, and how they were a sort of microcosm for the Industrial Revolution as a whole. Prior to the invention of steam-powered railroads, pretty much all locomotion had been muscle-powered. You either walked where you wanted to go or rode on an animal to get where you were going. The railroad changed human perception of time and space, making long-distance travel much faster and easier. Railroads also changed habits, including increasing reading. People needed some sort of distraction to ensure they didn't have to talk to other people on the train. Like any new technology, railroads also scared people. All kinds of fears surrounded rail travel, but over time, people got over them. And the quality of boiler manufacturing improved, so the trains exploded less often, which also made people feel safer.