Free speech not only enables free citizens to communicate with each other, it is a necessary condition for thinking about the world and discovering the truth of complex and novel phenomena. Even errors cannot be recognized as such unless we are free to make them and learn from them. If citizens are forbidden from communicating (by oral and written speech) with each other, they cannot ascertain what is going on in the world, but are obliged to accept the representations made by their rulers. Every tyrant in history has consolidated and extended his power by abridging the freedom of speech.