If a group of people are uneducated then it means they are illiterate. They can neither read or write. It's much easier to keep people in the dark if they don't know how to read or write. It is a form of oppression in another form.
Johannes Gutenburg created the printing press during the renaissance. It was important because it made the mass production of printed materials possible. It also lead to a much wider dissemination of knowledge and literacy throughout the socioeconomics classes.