It was during the Brezhnev Era that Suslov was given the unofficial title "Chief Ideologue of the Communist Party". Suslov spent much time in memorializing the legacies of Vladimir Lenin, Karl Marx and Friedrich Engels. However, Suslov followed the party line and supported the retreat from some of the beliefs of Marxism-Leninism. Examples of ideological retreat include the end of single, Party-approved natural science versions of biology, chemistry and physics. There still existed a tight ideological control over literature. This included not only literature critical of Soviet rule: much of Lenin's work was also routinely censored.