From Lenin’s Left-wing Communism: an Infantile Disorder (1920)
The years of preparation for revolution (1903–05)
The approach of a great storm was sensed everywhere. All classes were in a state of ferment and preparation. Abroad, the press of the political exiles discussed the theoretical aspects of all the fundamental problems of the revolution. Representatives of the three main classes, of the three principal political trends—the liberal-bourgeois, the petty-bourgeois-democratic (concealed behind “social-democratic” and “social-revolutionary” labels ), and the proletarian-revolutionary—anticipated and prepared the impending open class struggle by waging a most bitter struggle on issues of programme and tactics. All the issues on which the masses waged an armed struggle in 1905–07 and 1917–20 can (and should) be studied, in their embryonic form, in the press of the period. Among these three main trends there were, of course, a host of intermediate, transitional or half-hearted forms. It would be more correct to say that those political and ideological trends which were genuinely of a class nature crystallised in the struggle of press organs, parties, factions and groups; the classes were forging the requisite political and ideological weapons for the impending battles.
The years of revolution (1905–07).
All classes came out into the open. All programmatical and tactical views were tested by the action of the masses. In its extent and acuteness, the strike struggle had no parallel anywhere in the world. The economic strike developed into a political strike, and the latter into insurrection. The relations between the proletariat, as the leader, and the vacillating and unstable peasantry, as the led, were tested in practice. The Soviet form of organisation came into being in the spontaneous development of the struggle. The controversies of that period over the significance of the Soviets anticipated the great struggle of 1917–20. The alternation of parliamentary and non-parliamentary forms of struggle, of the tactics of boycotting parliament and that of participating in parliament, of legal and illegal forms of struggle, and likewise their interrelations and connections—all this was marked by an extraordinary wealth of content. As for teaching the fundamentals of political science to masses and leaders, to classes and parties alike, each month of this period was equivalent to an entire year of “peaceful” and “constitutional” development. Without the “dress rehearsal” of 1905, the victory of the October Revolution in 1917 would have been impossible.
The years of reaction (1907–10)
Tsarism was victorious. All the revolutionary and opposition parties were smashed. Depression, demoralisation, splits, discord, defection, and pornography took the place of politics. There was an ever greater drift towards philosophical idealism; mysticism became the garb of counter-revolutionary sentiments. At the same time, however, it was this great defeat that taught the revolutionary parties and the revolutionary class a real and very useful lesson, a lesson in historical dialectics, a lesson in an understanding of the political struggle, and in the art and science of waging that struggle. It is at moments of need that one learns who one’s friends are. Defeated armies learn their lesson.
Victorious tsarism was compelled to speed up the destruction of the remnants of the pre-bourgeois, patriarchal mode of life in Russia. The country’s development along bourgeois lines proceeded apace. Illusions that stood outside and above class distinctions, illusions concerning the possibility of avoiding capitalism, were scattered to the winds. The class struggle manifested itself in a quite new and more distinct way.
The revolutionary parties had to complete their education. They were learning how to attack. Now they had to realise that such knowledge must be supplemented with the knowledge of how to retreat in good order. They had to realise—and it is from bitter experience that the revolutionary class learns to realise this—that victory is impossible unless one has learned how to attack and retreat properly. Of all the defeated opposition and revolutionary parties, the Bolsheviks effected the most orderly retreat, with the least loss to their “army”, with its core best preserved, with the least significant splits (in point of depth and incurability), with the least demoralisation, and in the best condition to resume work on the broadest scale and in the most correct and energetic manner. The Bolsheviks achieved this only because they ruthlessly exposed and expelled the revolutionary phrase-mongers, those who did not wish to understand that one had to retreat, that one had to know how to retreat, and that one had absolutely to learn how to work legally in the most reactionary of parliaments, in the most reactionary of trade unions, co-operative and insurance societies and similar organisations.
The years of revival (1910–14).
At first progress was incredibly slow, then, following the Lena events of 1912, it became somewhat more rapid. Overcoming unprecedented difficulties, the Bolsheviks thrust back the Mensheviks, whose role as bourgeois agents in the working-class movement was clearly realised by the entire bourgeoisie after 1905, and whom the bourgeoisie therefore supported in a thousand ways against the Bolsheviks. But the Bolsheviks would never have succeeded in doing this had they not followed the correct tactics of combining illegal work with the utilisation of “legal opportunities”, which they made a point of doing. In the elections to the arch-reactionary Duma, the Bolsheviks won the full support of the worker curia.
The First Imperialist World War (1914–17).
Legal parliamentarianism, with an extremely reactionary “parliament”, rendered most useful service to the Bolsheviks, the party of the revolutionary proletariat. The Bolshevik deputies were exiled to Siberia.  All shades of social-imperialism, social-chauvinism, social-patriotism, inconsistent and consistent internationalism, pacifism, and the revolutionary repudiation of pacifist illusions found full expression in the Russian émigré press. The learned fools and the old women of the Second International, who had arrogantly and contemptuously turned up their noses at the abundance of “factions” in the Russian socialist movement and at the bitter struggle they were waging among themselves, were unable—when the war deprived them of their vaunted “legality” in all the advanced countries— to organise anything even approximating such a free (illegal) interchange of views and such a free (illegal) evolution of correct views as the Russian revolutionaries did in Switzerland and in a number of other countries. That was why both the avowed social-patriots and the “Kautskyites” of all countries proved to be the worst traitors to the proletariat. One of the principal reasons why Bolshevism was able to achieve victory in 1917–20 was that, since the end of 1914, it has been ruthlessly exposing the baseness and vileness of social-chauvinism and “Kautskyism” (to which Longuetism [4,5] in France, the views of the Fabians  and the leaders of the Independent Labour Party  in Britain, of Turati in Italy, etc., correspond), the masses later becoming more and more convinced, from their own experience, of the correctness of the Bolshevik views.
The second revolution in Russia (February to October 1917).
Tsarism’s senility and obsoleteness had (with the aid of the blows and hardships of a most agonising war) created an incredibly destructive force directed against it. Within a few days Russia was transformed into a democratic bourgeois republic, freer—in war conditions—than any other country in the world. The leaders of the opposition and revolutionary parties began to set up a government, just as is done in the most “strictly parliamentary” republics; the fact that a man had been a leader of an opposition party in parliament—even in a most reactionary parliament—facilitated his subsequent role in the revolution.
In a few weeks the Mensheviks and Socialist-Revolutionaries thoroughly assimilated all the methods and manners, the arguments and sophistries of the European heroes of the Second International, of the ministerialists  and other opportunist riff-raff. Everything we now read about the Scheidemanns and Noskes, about Kautsky and Hilferding, Renner and Austerlitz, Otto Bauer and Fritz Adler, Turati and Longuet, about the Fabians and the leaders of the Independent Labour Party of Britain—all this seems to us (and indeed is) a dreary repetition, a reiteration, of an old and familiar refrain. We have already witnessed all this in the instance of the Mensheviks. As history would have it, the opportunists of a backward country became the forerunners of the opportunists in a number of advanced countries.
If the heroes of the Second International have all gone bankrupt and have disgraced themselves over the question of the significance and role of the Soviets and Soviet rule; if the leaders of the three very important parties which have now left the Second International (namely, the German Independent Social-Democratic Party,  the French Longuetists and the British Independent Labour Party) have disgraced themselves and become entangled in this question in a most “telling” fashion; if they have all shown themselves slaves to the prejudices of petty-bourgeois democracy (fully in the spirit of the petty-bourgeois of 1848 who called themselves “Social-Democrats”)—then we can only say that we have already witnessed all this in the instance of the Mensheviks. As history would have it, the Soviets came into being in Russia in 1905; from February to October 1917 they were turned to a false use by the Mensheviks, who went bankrupt because of their inability to understand the role and significance of the Soviets; today the idea of Soviet power has emerged throughout the world and is spreading among the proletariat of all countries with extraordinary speed. Like our Mensheviks, the old heroes of the Second International are everywhere going bankrupt, because they are incapable of understanding the role and significance of the Soviets. Experience has proved that, on certain very important questions of the proletarian revolution, all countries will inevitably have to do what Russia has done.
Despite views that are today often to be met with in Europe and America, the Bolsheviks began their victorious struggle against the parliamentary and (in fact) bourgeois republic and against the Mensheviks in a very cautious manner, and the preparations they made for it were by no means simple. At the beginning of the period mentioned, we did not call for the overthrow of the government but explained that it was impossible to overthrow it without first changing the composition and the temper of the Soviets. We did not proclaim a boycott of the bourgeois parliament, the Constituent Assembly, but said—and following the April (1917) Conference of our Party began to state officially in the name of the Party—that a bourgeois republic with a Constituent Assembly would be better than a bourgeois republic without a Constituent Assembly, but that a “workers’ and peasants’ ” republic, a Soviet republic, would be better than any bourgeois-democratic, parliamentary republic. Without such thorough, circumspect and long preparations, we could not have achieved victory in October 1917, or have consolidated that victory.