The book is not a single-authored treatise by Lassalle but an edited collection of letters exchanged between Ferdinand Lassalle and Karl Marx. Its substance is the correspondence itself: letters written by each man to the other, together with the editorial framing that presents them as documents. The volume does not narrate either man’s life continuously; it allows the relationship, the political disagreements, and the practical preoccupations of the correspondents to emerge through the exchange.
The letters cover the period of their political acquaintance and collaboration through Lassalle’s emergence as an independent figure in the German workers’ movement, ending with the final phase of their correspondence before Lassalle’s death. They are not confined to high theory. They mix political analysis with personal news, publishing problems, financial requests, health complaints, travel plans, censorship, police surveillance, and comments on mutual acquaintances. Marx writes from the standpoint of his exile and his work on political economy; Lassalle writes from the context of Prussian legal and political agitation and his efforts to build a workers’ organization. The collection documents both initial cooperation and growing estrangement.
A major theme is theoretical disagreement. The letters discuss Hegelian philosophy, political economy, wages, credit, cooperation, the state, and the tasks of a workers’ party. Lassalle seeks Marx’s judgment on his manuscripts and political plans, while Marx repeatedly objects to Lassalle’s theoretical formulations and political tactics. Marx’s criticisms of Lassalle’s economic and philosophical pretensions, including his reaction to Lassalle’s writings on political economy and law, are part of the exchange. The correspondence also records Marx’s suspicion of Lassalle’s ambition and his doubts about Lassalle’s state-oriented strategy for the workers’ movement.
Another major theme is political strategy. Lassalle’s plans for an independent workers’ organization, his constitutional and legal campaigns, and his sense of himself as a leader are discussed and contested. Marx and Engels are frequent points of reference; Marx’s letters convey his reservations about Lassalle’s methods, his self-presentation, and his willingness to negotiate with Prussian authorities. The collection shows how political differences became personal estrangement.
The book is therefore a documentary source rather than a systematic exposition. It contains no continuous narrative of either man’s life and does not continue beyond the correspondence’s own horizon. Its contents are the letters themselves: a record of friendship, collaboration, theoretical argument, practical requests, and political rupture between two central figures of nineteenth-century socialism.
Taken together, the letters have a significance beyond the sum of their topics: they are a primary record of how socialist theory was argued out in private correspondence, where doctrinal differences were entangled with tactical decisions, organizational rivalries, and personal confidence. The volume shows Marx’s critique of Lassalleanism being formed in argument—through objections to Lassalle’s economic categories, his conception of the state’s role, and his claims to leadership—rather than as a finished doctrine. It also shows Lassalle’s position as a coherent enough challenge to require sustained response: a rival conception of workers’ politics centered on legal agitation, association, and state action. For the reader, the book’s value lies in this immediacy: it preserves the unfinished, situational texture of the relationship and makes visible the private mediation through which public socialist positions were transmitted. The collection therefore functions as a source for the intellectual history of the German workers’ movement and for the study of Marx’s polemical self-definition against a contemporary rival.
