Aurora’s Reviews > Marx and Marxism > Status Update

To my mind, the reason Marx is so important is his and his followers' contribution being one half of the foundation of the SPD, the first modern socialist part and really the first mass political party in history. The other major contributor being his rival Lasalle and followers. Marx's insights are interesting, but his real historical importance imo is in the organizational geneaology, in the First International as well as the influence of his followers and associates on the Second, which included a huge number of influential left-wing parties in Europe. The Bolsheviks grew out of a particular split among the Marx-influenced Social Democrats, but were hardly his only heirs, organizationally or intellectually (though they liked to pose as such).

But I haven't read a good single book on this to recommend.