The "cultural revolution," which lasted from May 1966 to October 1976, was responsible for the most severe setback and the heaviest losses suffered by the Party, the State and the people since the founding of the People's Republic. It was initiated and led by Comrade Mao Zedong.
His principal theses were that many representatives of the bourgeoisie and counter-revolutionary revisionists had sneaked into the Party, the government, the army, and cultural circles, and that the leadership in a fairly large majority of organizations and departments was no longer in the hands of Marxists and the people; that Party-persons in power taking the capitalist road had formed a bourgeois headquarters inside the Central Committee, which pursued a revisionist political and organizational line and had agents in all provinces, municipalities and autonomous regions, as well as in all central departments; that since the forms of struggle adopted in the past had not been able to solve this problem, the power usurped by the capitalist roaders could be recaptured only by carrying out a great cultural revolution, by openly and fully mobilizing the broad masses from the bottom up to expose these sinister phenomena; and that the "cultural revolution" was in fact a great political revolution in which one class would overthrow another, a revolution that would have to be waged time and again.
The history of the "cultural revolution" proved that Comrade Mao Zedong's principal theses for initiating this revolution conformed neither to Marxism-Leninism nor to Chinese reality. They represent an entirely erroneous appraisal of the prevailing class relations and political situation in the Party and state.
Practice has shown that the "cultural revolution" did not in fact constitute a revolution or social progress in any sense, nor could it possibly have done so.
Comrade Mao Zedong's personal leadership characterized by "Left" errors took the place of the collective leadership of the Central Committee, and the cult of Comrade Mao Zedong was frenziedly pushed to an extreme.
Chief responsibility for the grave "Left" error of the "cultural revolution," comprehensive in magnitude and protracted in duration, does indeed lie with Comrade Mao Zedong. But after all it was the error of a great proletarian revolutionary.
In his later years, he still remained alert to safeguarding the security of the country, stood up to the pressure of the social-imperialists, pursued a correct foreign policy, firmly supported the just struggles of all peoples, outlined the correct strategy of the three worlds and advanced the important principle that China would never seek hegemony.
Source: The Resolution on Certain Questions in the History of Our Party Since the Founding of the People's Republic of China, June 27, 1981