THE LEFT LIBERAL JOURNALIST Hellmut von Gerlach remarked that Eisner, in his four-year tenure as political editor of the General- Anzeiger, won for the publication “a significance extending far beyond the range of a provincial paper.” Hesse had been annexed by Prussia after siding with Austria in Bismarck's war for Schleswig-Holstein; in its intellectual capital Eisner gloried in deprecating the Prussian arrogance and ambition personified by the German emperor. In lead articles for the paper, Berlin weeklies, and the liberal daily Vossische Zeitung ([Christian Friedrich] Voß Newspaper) he achieved his earmark style “somewhere between Heinrich Heine and Kurt Tucholsky.” In light of Eisner's coruscating wit and irony historian Allan Mitchell surmised: “Had he not been the editor of a provinical newspaper, he might well have earned his living by writing for one of Berlin's political cabarets.” Eisner's years in Marburg were in many respects the happiest of his life, a period of both respite and preparation, alive with the promise of family, friendship, intellectual growth, and meaningful work. A regular income freed him from the anxiety of the past, Lisbeth gave birth to three of their children there, and Eisner was drawn into the circle of intellectuals around philosophy professor Hermann Cohen, master of the neo-Kantian Marburg School whose thinking shaped a generation of “reform” socialists. The association with Cohen, his colleagues, and students channeled Eisner's already strong philosophical and political inclinations; “he began to define his socialism as a Kantian ethical socialism.” And through his political involvement with Bader he learned the practical application of his ideas.

Hermann Cohen had succeeded his patron Friedrich Albert Lange, enunciator of ethical socialism, as philosophy chair at Marburg in 1876. Once Eisner was settled, he determined to take advantage of his proximity to the great Jewish scholar who, continuing Lange's work, was in the process of explicating systematically that socialism has both its moral justification and philosophical fundament in Kantian ethics rather than in Hegel's ideal metaphysics or Marx's historical materialism. Cohen believed that philosophy, not science, is the vehicle for studying ethics, and that man—specifically, the individual and his associations—is the focus of the discipline. The principles that govern the conduct of individuals in their dealings with others are ethics, and moral values determine politics and economics rather than vice versa.