THE idea of publishing the selected letters of Marx and Engelscomes from Lenin. Hfe repeatedly stressed the great scientificand political value of the correspondence of the founders ofscientific Communism.

In I913,Lenin wrotc with regard to the correspondencebetween Marx and Engels，which had then just been pub-lished :

“In this correspondence it is not merely that Marx andEngels here stand out before the reader in striking reliefand in all their greatness.The extremely rich theoreticalcontent of Marxism is unfolded most vividly, since Marx andEngels again and again return in the letters to the mostdiverse aspects of their teaching, emphasising and explaining—at times discussing with each other and proving 'to eachother--the most recent (in relation to previous views), mostimportant and most difficult points.

The history of the labour movement throughout theworld,at its most important moments and in the mostessential points, passesbefore the reader with strikingvividness."Even more valuable is the history of the politicsof the working class.Prompted by most 'diverse occur-rences,in various countries,in the old world and in thenew,and at different historical moments，Marx and Engelswould discuss what was most fundamental in the formula-tion of questions concerning the political tasks of the workingclass. Now the epoch covered by the correspondence was justthe epoch when the working class became demarcatedt frombourgeois democracy, the epoch of the rise of an independentlabour movement, the epoch when the basic principles of pro-letarian tactics and policy were being determined.The more frequently one observes nowadays how the labour move-ment in 'various countries suffers from opportunism,inconsequence of the stagnation and decay of the bourgeoisie,in consequence of thc fact that the labour leaders are en-grossed in the trivialities of the day, etc.-the more valuablcbecomes thc great wealth of material contained in thecorrespondence，displaying as it does the most profoundunderstanding of the fundamental revolutionary aims of theproletariat and an unusually flexible definition of any givenproblem of tactics，frorn the point of view of these revolu-tionary aims and without the slightest concession to oppor-tunism or revolutionary phrascology.