Freedom is the recognition of necessity.

What each individual wills is obstructed by everyone else, and what emerges is something that no one willed.

...it was always our view that in order to attain this [proletarian revolution] and the other far more important aims of the future social revolution, the working class must first take possession of the organised political power of the state and by its aid crush the resistance of the capitalist class and organise society anew.

Freedom does not consist in any dreamt-of independence from natural laws, but in the knowledge of these laws, and in the possibility this gives of systematically making them work towards definite ends.

In science, each new point of view calls forth a revolution in nomenclature.

It is a curious fact that with every great revolutionary movement the question of 'free love' comes into the foreground.

By bourgeoisie is meant the class of modern capitalists, owners of the means of social production and employers of wage labor. By proletariat, the class of modern wage laborers who, having no means of production of their own, are reduced to selling their labor power in order to live.