Printing press
The German Johannes Gutenberg invented the printing press around 1440. Key to its development was the hand mold, a new molding technique that enabled the rapid creation of large quantities of metal movable type. Printing presses exponentially increased the speed with which book copies could be made, and thus they led to the rapid and widespread dissemination of knowledge for the first time in history. Twenty million volumes had been printed in Western Europe by 1500.
Among other things, the printing press permitted wider access to the Bible, which in turn led to alternative interpretations, including that of Martin Luther, whose “95 Theses” a document printed by the hundred-thousand sparked the Protestant Reformation.