But even in its most elementary form, the spontaneous class struggle of the wage earners under capitalism leaves behind a residue in the form of a consciousness crystallised in a process of continuous organisation. Most of the mass is active only during the struggle; after the struggle it will sooner or later retreat into private life (i.e., "into the struggle for existence"). What distinguishes the workers vanguard from this mass is the fact that even during a lull in the struggle it does not abandon the front lines of the class struggle but continues the war, so to speak, "by other means." It attempts to solidify the resistance funds generated in the struggle into ongoing resistance funds - i.e., into unions.  By publishing workers newspapers and organising educational groups for workers, it attempts to crystallise and heighten the elementary class consciousness generated in the struggle. It thus helps give form to a factor of continuity, as opposed to the necessarily discontinuous action of the mass,  and to a factor of consciousness, as opposed to the spontaneity of the mass movement in and of itself.
However, advanced workers are driven to continuous organisation and growing class consciousness less by theory, science, or an intellectual grasp of the social whole than by the practical knowledge acquired in struggle. Since the struggle shows  that the dissolving of the resistance funds after each strike damages the effectiveness of the strike and the working sums in hand, attempts are made to go over to the permanent strike fund. Since experience shows an occasional leaflet to have less effect than a regular newspaper, the workers press is born. Consciousness arising directly out of the practical experience of struggle is empirical and pragmatic consciousness, which can enrich action to a certain extent, but which is far inferior to the effectiveness, of a scientifically global consciousness, i.e., of theoretical understanding.
Based on its general theoretical understanding the revolutionary vanguard organisation can consolidate and enrich this higher consciousness, provided it is able to establish ties to the class struggle, i.e., provided it does not shrink from the hard test of verifying theory in practice, of reuniting theory and practice. From the point of view of mature Marxism - as well as that of Marx himself and Lenin - a "true" theory divorced from practice is as much an absurdity as a "revolutionary practice" that is not founded on a scientific theory. This in no way diminishes the decisive importance and absolute necessity for theoretical production. It simply emphasises the fact that wage-earning masses and revolutionary individuals, proceeding from different starting points and with a different dynamic, can bring about the unity of theory and practice.
This process can be summarised in the following diagram:
If we rearrange this diagram so that certain conclusions can be drawn from it, we get the following:
This formal diagram reveals a series of conclusions about the dynamics of class consciousness which were already anticipated in the analysis but which only now obtain their full value. The collective action of the advanced workers (the "natural leaders" of the working class in the shops) is, relatively speaking, more difficult to attain because it can be aroused neither through pure conviction (as with the revolutionary nuclei) nor through purely spontaneous explosiveness (as with the broad masses). It is precisely the struggle experience - the important motivating factor in the actions of the advanced workers - that makes them much more careful and cautious before they undertake action on a broad scale. They have already digested the lessons of past actions and know that an explosion is not at all sufficient for them to be able to reach their goal. They have fewer illusions about the strength of the enemy (not to mention his "generosity") and about the durability of the mass movement. The greatest "temptation" of economism can be traced to this very point.
To summarise: the building of the revolutionary class party is the merging of the consciousness of the revolutionary nuclei with that of the advanced workers. The ripening of a prerevolutionary situation (of potentially revolutionary explosion) is the merging of action by the broad masses with that of the advanced workers. A revolutionary situation - i.e., the possibility of a revolutionary conquest of power - arises when a merging of actions by the vanguard and the masses with the consciousness of the vanguard and revolutionary layers has been accomplished.  For the broad masses, the elementary class struggle arising from the contradictions of the capitalist mode of production is always kindled only by matters of immediate concern. The same is true for all mass actions, even political ones. Thus the problem of the broad mass struggle growing over into a revolutionary one depends not only on a quantitative factor, but also on a qualitative one. This requires the existence of sufficiently advanced workers within the masses or the mass movement who, on the basis of the stage of consciousness they have already reached, are capable of sweeping broader masses into action around objectives that challenge the continued existence of bourgeois society and the capitalist mode of production.
This also highlights the central importance of transitional demands,  the strategic position of advanced workers already trained in propagating these transitional demands, and the historical importance of the revolutionary organisation, which alone is capable of working out a comprehensive program of transitional demands corresponding to the objective historical conditions, as well as to the subjective needs, of the broadest layers of the mass. A successful proletarian revolution is only possible if all these factors are successfully combined.
We have already stated that Lenin’s theory of organisation is, in fact, above all a theory of revolution. To have misunderstood this is the great weakness of Rosa Luxemburg’s polemic against Lenin in 1903-1904. It is characteristic that the concept of centralisation which is attacked in the essay "Organisational Question of Social Democracy" is - and this is clear if it is read attentively - a purely organisational one. (Yet while it is attacked, it is also confirmed. On this point modern "Luxemburgists" ought to read their "Rosa" more carefully and more thoroughly!) Lenin is accused of advocating an "ultracentralist" line, of dictating the composition of local party committees, and of wishing to stymie any initiative by lower party units. 
When we turn to the Leninist theory of organisation as developed by Lenin himself, however, we see that the emphasis is by no means upon the formal, organisational side of centralisation but upon its political and social function. At the heart of What is to Be Done? is the concept of the transformation of proletarian class consciousness into political class consciousness by means of a comprehensive political activity that raises and, from a Marxist point of view, answers all questions of internal and external class relations:
"In reality, it is possible to ‘raise the activity of the working masses’ only when this activity is not restricted to ‘political agitation on an economic basis.’ A basic condition for the necessary expansion of political agitation is the organisation of comprehensive political exposure. In no way except by means of such exposures con the masses be trained in political consciousness and revolutionary activity."
The consciousness of the working masses cannot be genuine class consciousness, unless the workers learn, from concrete, and above all from topical, political facts and events to observe every other social class in all the manifestations of its intellectual, ethical, and political life; unless they learn to apply in practice the materialist analysis and the materialist estimate of all aspects of the life and activity of all classes, strata, and groups of the population. Those who concentrate the attention, observation, and consciousness of the working class exclusively, or even mainly, upon itself alone are not Social Democrats; for the self knowledge of the working class is indissolubly bound up, not solely with a fully clear theoretical understanding - it would be even truer to say, not so much with the theoretical, as with the practical, understanding - of the relationships between all the various classes of modern society, acquired through the experiences of political life. 
And it is for the same reason that Lenin emphasises so strongly the absolute necessity for the revolutionary party to make all progressive demands and movements of all oppressed social layers and classes its own - even "purely democratic" ones. The central strategic plan advanced by Lenin in What is to Be Done?  is therefore one of party agitation that unites all elementary, spontaneous, dispersed and "merely" local or sectional protests, revolts and movements of resistance. The emphasis of centralisation clearly lies in the political and not in the formal, organisational sphere. The aim of formal organisational centralisation is only to make possible the realisation of this strategic plan.
Although she does not recognise this essence of Lenin’s "centralism," Luxemburg is compelled in her polemic to indirectly counterpose to it another conception of the formation of political class consciousness and the preparation of revolutionary situations. Her doing so emphasises even more poignantly how utterly wrong she was in this debate. Luxemburg’s concept that "the proletarian army is recruited and becomes aware of its objectives in the course of the struggle itself"  has been completely refuted by history. In even the broadest, longest and most vigorous of workers struggles, the working masses have not gained a clear understanding of the tasks of the struggle, or did so only to an insufficient degree. (One need only recall the French general strikes of 1936 and 1968, the struggles of the German workers from 1918 to 1923, the great struggles of the Italian workers in 1920, 1948 and 1969, as well as the prodigious class struggles in Spain from 1931 to 1937, to mention only these four European countries.)
Experience in struggle is by no means sufficient for clarity on the tasks of a broad prerevolutionary, or even a revolutionary, mass struggle to be attained. Not only, of course, are these tasks connected to the immediate motives that set off the struggle, but they can be grasped only by means of a comprehensive analysis of the overall social development, of the historical position achieved by the capitalist mode of production and its internal contradictions, and of the national and international relationship of forces between classes. Without protracted and consistent preparation, without the education of hundreds and thousands of advanced workers in the spirit of a revolutionary program, and without the practical experience accumulated over the years by these advanced workers through attempting to bring this program to the broad masses, it would be absolutely illusory to assume that suddenly, overnight so to speak, with the mere aid of mass actions, a consciousness equal to the demands of the historical situation could be created among these broad masses.
Actually, one could turn Luxemburg’s proposition around and say that the proletarian army will never reach its historic objectives if the necessary education, schooling and testing of a proletarian vanguard in the working out and agitational application of the revolutionary program in struggle has not taken place before the outbreak of the broadest mass struggles, which by themselves create only the possibility of the broad masses attaining revolutionary consciousness. That is the tragic lesson of the German revolution after the first world war, which was crushed precisely because of the lack of such a trained vanguard.
The objective of Lenin’s strategic plan is to create such a vanguard through an organic union of individual revolutionary nuclei with the vanguard of the proletariat. Such a fusion is impossible without a comprehensive political activity that takes the advanced workers beyond the confines of a horizon limited to the trade union or the factory. Empirical data available to us today confirm that Lenin’s party, before and during the revolution of 1905 and after the mass movement began to pick up again in 1912, was in fact such a party. 
To fully grasp the profoundly revolutionary nature of Lenin’s strategic plan, it must be approached from yet another point of view. Any concept based on the probability, if not the inevitability, of a revolution occurring in the not too distant future, must inevitably deal with the question of a direct collision with state power, i.e., the question of the conquest of political power. As soon as this difficulty is built into the concept, however, the result is one more argument in favour of centralisation. Lenin and Luxemburg agreed that capitalism itself and the bourgeois state exert, a powerful centralising influence on modern society,  and that it is in turn absolutely illusory to think that this centralised state power can be gradually dismantled, as for instance a wall can be taken apart brick by brick.
In the final analysis, the ideological essence of the reformism and revisionism rejected by Luxemburg and Lenin with equal passion  was rooted in the illusion that this could be done. Once the question of the conquest of state power is no longer placed far off in the distance, however, but is recognised to be an objective for the near or not-too-distant future, the revolutionary is immediately confronted with the question of the means necessary for achieving the revolutionary conquest of power. Here again Luxemburg misconstrued the import of Lenin’s purely polemical use of the notion of "Jacobins inseparably linked to the organisation of the class-conscious proletariat." What Lenin meant with this idea was certainly not a brand of Blanquist conspirators but an advanced group oriented, like the Jacobins, toward an unremitting attempt to carry out the revolutionary tasks, one that does not permit itself to be diverted from concentrating on these tasks by the inevitable conjunctural ebb and flow of the mass movement.
Yet to do justice to Luxemburg it must be added that, in the first place, she took up - in fact had to take up - this question from a different historical viewpoint since, by 1904, she was already influenced more by German than by Russian or Polish reality; and second, that she completely drew the necessary conclusions in the Leninist sense as soon as it became clear that in Germany, too the coming of the revolution was an immediate possibility. 
The young Trotsky likewise made a serious error in his polemic against Lenin when he reproached him for this "substitutionism," i.e., the replacement of the initiative of the working class with that of the party alone.  If we remove the core of this reproach from its polemical shell, we find here too an idealistic, inadequate conception of the evolution of the class consciousness of the proletariat: "Marxism teaches that the interests of the proletariat are determined by its objective conditions of life. These interests are so powerful and so unavoidable that they eventually (!) compel the proletariat to bring them into the scope of its consciousness, i.e., to make the realisation of its objective interests into its subjective interest."  Today it is easy to see what a naively fatalistic optimism was concealed in this inadequate analysis. Immediate interests are here put on the same level with historical interests, i.e., with the unravelling of the most complex questions of political tactics and strategy. The hope that the proletariat will "eventually" recognise its historical interests seems rather shallow when compared to the historical catastrophes that have arisen because, in the absence of an adequate revolutionary leadership, the proletariat was not even able to accomplish the revolutionary tasks of the here and now.
The same naive optimism is even more strikingly manifested in the following passage from the same polemic:
The revolutionary social democrat is convinced not only of the inevitable (!) growth of the political party of the proletariat, but also of the inevitable (!) victory of the ideas of revolutionary socialism within this party. The first proof lies in the fact that the development of bourgeois society spontaneously leads the proletariat to politically demarcate itself; the second in the fact that the objective tendencies and the tactical problems of this demarcation find their best, fullest and deepest expression in revolutionary socialism, i.e., Marxism. 
This quotation makes clear that what the young Trotsky was championing in his polemic against Lenin was the "old, tested tactic" and the naive "belief in the inevitability of progress" ŕ la Bebel and Kautsky which prevailed in the international Social Democracy from the time of Marx’s death until the first world war. Lenin’s concept of class consciousness was incomparably richer, more contradictory and more dialectical precisely because it was based on a keen grasp of the relevance of the revolution for the present (not "finally some day" but in the coming years). To round out the historical development it must be added that following the outbreak of the Russian revolution in 1917, Trotsky fully adopted Lenin’s analysis of the formation of proletarian class consciousness and hence also Lenin’s theory of organisation, and until his death he stubbornly defended them against all sceptics and arch-pessimists (who claimed to detect in them the "embryo" of Stalinism). Thus he wrote in his last, unfinished manuscript:
A colossal factor in the maturity of the Russian proletariat in February or March 1917 was Lenin. He did not fall from the skies. He personified the revolutionary tradition of the working class. For Lenin’s slogans to find their way to the masses, there had to exist cadres, even though numerically small at the beginning; there had to exist the confidence of the cadre in the leadership, a confidence based upon the entire experience of the past. To cancel these elements from one’s calculations is simply to ignore the living revolution, to substitute for it an abstraction, the ‘relationship of forces,’ because the development of the revolution precisely consists of this, that the relationship of forces keeps incessantly and rapidly changing under the impact of the changes in the consciousness of the proletariat, the attraction of backward layers to the advanced, the growing assurance of the class in its own strength. The vital mainspring in this process is the party, just as the vital mainspring in the mechanism of the party is its leadership.