„Social Democratic centralism cannot be based on the mechanical subordination and blind obedience of the party membership to the leading party center. […] The Social Democratic movement cannot allow the erection of an air-tight partition between the class-conscious nucleus of the proletariat already in the party and its immediate popular environment, the nonparty sections of the proletariat.“

— Rosa Luxemburg
„For Lenin, the difference between the Social Democracy and Blanquism is reduced to the observation that in place of a handful of conspirators we have a class-conscious proletariat. He forgets that this difference implies a complete revision of our ideas on organization and, therefore, an entirely different conception of centralism and the relations existing between the party and the struggle itself.“
— Rosa Luxemburg
„he Party is the highest form of organisation of the proletariat. The Party is the principle guiding force within the class of the proletarians and among the organisations of that class. But it does not by any means follow from this that the Party can be regarded as an end in itself, as a self-sufficient force. The Party is not only the highest form of class association of the proletarians; it is at the same time an instrument in the hands of the proletariatfor achieving the dictatorship, when that has not yet been achieved and for consolidating and expanding the dictatorship when it has already been achieved. The Party could not have risen so high in importance and could not have exerted its influence over all other forms of organisations of the proletariat, if the latter had not been confronted with the question of power, if the conditions of imperialism, the inevitability of wars, and the existence of a crisis had not yet demanded the concentration of all the forces of the proletariat at one point, the gathering of all the threads of the revolutionary movement in one spot in order to overthrow the bourgeoisie and to achieve the dictatorship of the proletariat. The proletariat needs the Party first of all as its General Staff, which it must have for the successful seizure of power. It scarcely needs proof that without a party capable of rallying around itself the mass organisations of the proletariat, and of centralising the leadership of the entire movement during the progress of the struggle, the proletariat in Russia could not have established its revolutionary dictatorship.“
— Joseph Stalin
„The Party is carried on though the Soviets, which embrace the working masses, irrespective of occupation. The district congresses of Soviet are democratic institutions, the like of which even the best of the democratic republics of the bourgeois world have never known; through these con tresses, as well as by continually appointing class-conscious workers to various posts in the rural districts, the proletariat exercises its role of leader of the peasantry, gives effect to the dictatorship of the urban proletariat, wages, a systematic struggle against the rich, bourgeois, exploiting and profiteering peasantry, etc.“
— Vladimir Lenin
„But here is the "ego" of the Russian revolutionary again! Pirouetting on its head, it once more proclaims itself to be the all-powerful director of history — this time with the title of His Excellency the Central Committee of the Social Democratic Party of Russia.“
— Rosa Luxemburg
„The theory of "defeating" opportunist elements by the ideological struggle within the Party, the theory of "overcoming" these elements within the confines of a single party, is a rotten and dangerous theory, which threatens to condemn the Party to paralysis and chronic infirmity, threatens to leave the Party a prey to opportunism, threatens to leave the proletariat without a revolutionary party, threatens to deprive the proletariat of its main weapon in the fight against imperialism. Our Party could not have emerged on to the broad highway, it could not have seized power and organised the dictatorship of the proletariat, it could not have emerged victorious from the civil war, if it had had within its ranks people like Martov and Dan, Potresov and Axelrod. Our Party succeeded in achieving internal unity and unexampled cohesion of its ranks primarily because it was able to in good time to purge itself of the opportunist pollution, because it was able to rid its ranks of the Liquidators and Mensheviks. Proletarian parties develop and become strong by purging themselves of opportunists and reformists, social-imperialists and social-chauvinists, social-patriots and social-pacifists.“
— Joseph Stalin