Materialism, the belief that thought reflects the world, and does not create it, lay at the basis of his conception of history. “It is not the consciousness of men that determines their being, but, on the contrary, their social being which determines their consciousness” (SW i, 503).

The acorn contains within itself its own negation, and is thus contradictory. It is this contradiction, says Hegel, and only this contradiction, that allows it to grow.

Capitalism, for Marx, is a world in which the worker is dominated by the products of his labor, which have taken on the shape of an alien being, capital.

This, said Feuerbach, is at the root of all religion. Religion takes what are human powers—the ability to think, to act on and change the world, and so on—and transfers them to an imaginary being, God. Thus human beings turn their own powers into something alien from themselves.

capitalism is an exploitative social system whose contradictions must lead either to socialism or to barbarism, and that the only hope for humanity lies in the working class destroying the capitalist state machine and replacing it with its own rule.

The proposition that men and women are first and foremost producers radically challenged basic assumptions about society that had been accepted by almost all earlier thinkers.

“Man lives on nature—nature is his body, with which he must remain in continuous interchange if he is not to die” (CW iii, 275).

The dialectic was based on two assumptions. First, that “all things are contradictory in themselves.” Secondly, that “contradiction is at the root of all movement and life, and it is only insofar as it contains a contradiction that anything moves and has impulse and activity.”

Socialism is a good idea, people say, but it will never happen, because you can’t change human nature. Any attempt to create a society free of poverty, exploitation and violence is bound to run up against the fact that human beings are naturally selfish, greedy and aggressive.