On the other hand, Herbert Marcuse was a German philosopher, sociologist and political theorist associated with the Frankfurt School of critical theory. His work "Eros and Civilization" (1955) discusses the social meaning of biology—history seen not as a class struggle, but a fight against repression of our instincts. It argues that "advanced industrial society" (modern capitalism) is preventing us from reaching a non-repressive society "based on a fundamentally different experience of being, a fundamentally different relation between man and nature, and fundamentally different existential relations". It contends that Freud's argument that repression is needed by civilization to persist is mistaken as Eros is liberating and constructive. Marcuse argues that "the irreconcilable conflict is not between work (reality principle) and Eros (pleasure principle), but between alienated labour (performance principle) and Eros". Sex is allowed for "the betters" (capitalists) and for workers only when not disturbing performance. Marcuse believes that a socialist society could be a society without needing the performance of the poor and without as strong a suppression of our sexual drives—it could replace alienated labor with "non-alienated libidinal work" resulting in "a non-repressive civilization based on 'non-repressive sublimation'". During the 1960s, Marcuse achieved world renown as "the guru of the New Left", publishing many articles and giving lectures and advice to student radicals all over the world. He travelled widely and his work was often discussed in the mass media, becoming one of the few American intellectuals to gain such attention. Never surrendering his revolutionary vision and commitments, Marcuse continued to his death to defend the Marxian theory and libertarian socialism.