The printing press, and its proliferation a few hundred years ago.<p>Without it, the cost of copying information is enormous. When you can&#x27;t copy stuff cheaply, you end up copying only a few things. Like  what whoever is in power likes. Or whatever the accepted wisdom of the day is.<p>With it, you can have ideas, spread them, and get feedback from a lot of people. That goes for social ideas like liberalism, religious ideas like Protestantism, scientific ideas like gravity, and technological ideas like all the ones on HN.<p>You also get away from authority. If you have some new thoughts about how government should be organised, it&#x27;s a lot harder to stop you telling everyone.