criticism under the classical "double hundred" slogan "Let a hundred flowers bloom, let the hundred schools of thought contend." "Let a hundred flowers bloom" applied to the development of the arts, and "let the hundred schools of thought contend" encouraged the development of science. The initiation of this campaign was followed by the publication in early 1957 of Mao Zedong's essay "On the Correct Handling of Contradictions among the People," in which he drew a distinction between "constructive criticisms among the people" and "hateful and destructive criticism between the enemy and ourselves." In August 1957, when it was clear to the leadership that widespread criticism of the party and party cadres had gotten out of hand, the Anti-Rightist Campaign was launched to suppress all divergent thought and firmly reestablish orthodox ideology. Writers who had answered the party's invitation to offer criticisms and alternative solutions to China's problems were abruptly silenced, and many were sent to reform camps or internal exile. By the early 1960s, however, a few intellectuals within the party were bold enough to again propose policy alternatives, within stringent limits. Cultural Revolution When the Cultural Revolution began in 1966, party functionaries assumed positions of leadership at most research institutes and universities, and many schools were closed or converted to "soldiers', workers', and peasants' universities." Intellectuals, denounced as the "stinking ninth category," either were purged or had their work heavily edited for political "purity", which severely hampered most serious research and scholarship. Following the fall of Lin Biao, Minister of National Defense and Mao's heir apparent, in 1971, the atmosphere for intellectuals began to improve. Under the aegis of Zhou Enlai and later Deng Xiaoping, many intellectuals were restored to their former positions and warily resumed their pre-Cultural Revolution duties. In January 1975 Zhou Enlai set out his ambitious Four Modernizations program and solicited the support of China's intellectuals in turning China into a modern industrialized nation by the end of the century. Post-Mao Zedong development The Third Plenum of the Eleventh National Party Congress Central Committee in December 1978 officially made the Four Modernizations basic national policy and reemphasized the importance of intellectuals in achieving them. The policy of "seeking truth from facts" was stressed, and scholars and researchers were given freer rein to pursue scientific research. Most mainstream intellectuals were content to avoid political involvement and to take on the role of scholar- specialists within their spheres