But the class consciousness of the proletariat, the truth of the process ‘as subject’ is itself far from stable and constant; it does not advance according to mechanical 'laws’. It is the consciousness of the dialectical process itself: it is likewise a dialectical concept. For the active and practical side of class consciousness, its true essence, can only become visible in its authentic form when the historical process imperiously requires it to come into force, i.e. when an acute crisis in the economy drives it into action. At other times it remains theoretical and latent, corresponding to the latent and permanent crisis of capitalism: it confronts the individual questions and conflicts of the day with its demands, but as 'mere’ consciousness, as an 'ideal sum’, in Rosa Luxemburg’s phrase.
— Georg Lukács, History and Class Consciousness; “The Marxism of Rosa Luxemburg”, pp. 41-42