'"The theory of human nature." Is there such a thing as human nature? Of course there is. But there is only human nature in the concrete, no human nature in the abstract. In class society there is only human nature of a class character; there is no human nature above classes. We uphold the human nature of the proletariat and of the masses of the people, while the landlord and bourgeois classes uphold the human nature of their own classes, only they do not say so but make it out to be the only human nature in existence. The human nature boosted by certain petty-bourgeois intellectuals is also divorced from or opposed to the masses; what they call human nature is in essence nothing but bourgeois individualism, and so, in their eyes, proletarian human nature is contrary to human nature.'
Mao Zedong, Talks at the Yenan Forum on Literature and Art