What was the importance of the printing press in spreading press?

With the invention of the printing press people could get a book and read it. They didn't have to depend on the church or king to tell them about the world. It opened the door to ideas and thinking. They could write a book and tell others about their ideas, experiences, thinking, and to disagree with a government/king/church. When people can read/write/think they can't be kept slaves or enslaved.