The working classes in every country only learn to fight in the course of their struggles.

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.

Only to the rude ear of one who is quite indifferent does the song of a bird seem always the same.

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.

Self-criticism, cruel, unsparing criticism that goes to the very root of the evil, is life and breath for the proletarian movement.

The most revolutionary act is a clear view of the world as it really is.