a key trigger in the cultural revolution was the publication of a "dàzìbào" on 25 may 1966, by nie yuanzi (聂元梓/聶元梓) and others at peking university, claiming that the university was controlled by bourgeois anti-revolutionaries. the poster came to the attention of mao zedong, who had it broadcast nationally and published in the "people's daily". "dazibao" became a crucial tool in mao's struggle during the cultural revolution, and mao himself wrote his own "dazibao" at beijing university on 5 august 1966, calling on the people to "bombard the headquarters". big-character posters were soon ubiquitous, used for everything from sophisticated debate to satirical entertainment to rabid denunciation; being attacked in a big-character poster was enough to end one's career. one of the "four great rights" in the 1975 state constitution was the right to write "dàzìbào".