The fifteenth-century invention of the printing press had led to an explosion of knowledge, but it also granted new powers to anyone who could afford to produce pamphlets and books to shape public opinion. And while railroads boosted commerce, they also expanded the political sway of railroad magnates, allowing their companies to act like monopolies and exploit workers. For all the prosperity and convenience that some of the world’s greatest innovations have brought, they also gave rise to new regimes that reshaped society in ways both good and bad.