History is the only true teacher, the revolution the best school for the proletariat.
Freedom is always and exclusively freedom for the one who thinks differently.
Social democracy seeks and finds the ways, and particular slogans, of the workers' struggle only in the course of the development of this struggle, and gains directions for the way forward through this struggle alone.
Freedom only for the members of the government, only for the members of the Party - though they are quite numerous - is no freedom at all.
The working classes in every country only learn to fight in the course of their struggles.
The masses are the decisive element, they are the rock on which the final victory of the revolution will be built.
The masses are in reality their own leaders, dialectically creating their own development process.
Marxism is a revolutionary worldview that must always struggle for new revelations.
Social democracy... is only the advance guard of the proletariat, a small piece of the total working masses; blood from their blood, and flesh from their flesh.
The more that social democracy develops, grows, and becomes stronger, the more the enlightened masses of workers will take their own destinies, the leadership of their movement, and the determination of its direction into their own hands.
Only through the conscious action of the working masses in city and country can it be brought to life, only through the people's highest intellectual maturity and inexhaustible idealism can it be brought safely through all storms and find its way to port.
Bourgeois class domination is undoubtedly an historical necessity, but, so too, the rising of the working class against it. Capital is an historical necessity, but, so too, its grave digger, the socialist proletariat.