From What Does Spartacus Want? by Rosa Luxemburg on the Marxists Internet Archive:
The struggle for socialism has to be fought out by the masses, by the masses alone, breast to breast against capitalism; it has to be fought out by those in every occupation, by every proletarian against his employer. Thus only can it be a socialist revolution. ... Socialism will not be and cannot be inaugurated by decrees; it cannot be established by any government, however admirably socialistic. Socialism must be created by the masses, must be made by every proletarian. Where the chains of capitalism are forged, there must the chains be broken. That only is socialism, and thus only can socialism be brought into being.