That Johannes Gutenberg guy was on to something. He may not have been the first person to print texts on paper using movable type—systems in China and Korea predated his—but his printing press made it faster, and cheaper, to create a record of a thought. One by one, those thoughts spread across Europe, philosophy and science and poetry. They might have been a cause of the Renaissance, or simply a symptom, but ideas grew legs they'd never had before.