The Discourses of the States tell of King Li of Zhou, who used a shaman to watch for anyone who criticized him and had them killed. “The people of the capital did not dare to speak. On the road, they exchanged glances.” (国人莫敢言，道路以目)
The king told the Duke of Shao that he had stopped the criticism. The duke answered: “Blocking the mouths of the people is more dangerous than blocking a river.” The king did not listen. Three years later, the people drove him into exile.