— Rosa Luxemburg Polish Marxist theorist, socialist philosopher, and revolutionary 1871 - 1919
Context: 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. Freedom is always the freedom of dissenters. The essence of political freedom depends not on the fanatics of 'justice', but rather on all the invigorating, beneficial, and detergent effects of dissenters. If 'freedom' becomes 'privilege', the workings of political freedom are broken.
Die russische Revolution. Eine kritische Würdigung (1920) p. 109 <!-- and in Rosa Luxemburg - Gesammelte Werke Vol. 4, p. 359, Footnote 3, Dietz Verlag Berlin (Ost), 1983 -->
This contains probably her most famous statement: Freiheit ist immer Freiheit der Andersdenkenden, translated as "Freedom is always the freedom of dissenters."
Variant: Freedom is always and exclusively freedom for the one who thinks differently.