All that is real in human history becomes irrational in the process of time.

Thus at every step we are reminded that we by no means rule over nature like a conqueror over a foreign people, like someone standing outside nature - but that we, with flesh, blood and brain, belong to nature, and exist in its midst, and that all our mastery of it consists in the fact that we have the advantage over all other creatures of being able to learn its laws and apply them correctly.

Freedom is the recognition of necessity.

In a political struggle of class against class, organization of trade unions is the most important weapon.

The slave frees himself when, of all the relations of private property, he abolishes only the relation of slavery and thereby becomes a proletarian; the proletarian can free himself only by abolishing private property in general.

It is no longer a question anywhere of inventing interconnections from out of our brains, but of discovering them in the facts.

All that is real in human history becomes irrational in the process of time.