Moses (Moritz)[2] Hess (21 January 1812 – 6 April 1875)[1] was a German-Jewish philosopher, early communist and Zionist thinker.

Although they remained happily married until Hess' death,[2] Sibylle may have had an affair with Friedrich Engels while he was smuggling her from Belgium to France to be reunited with her husband.

He was a friend and important collaborator of Karl Marx, who was the editor of the Rheinische Zeitung, following his advice, and befriended also with Friedrich Engels.

According to George Lichtheim, Hess, who differed from Marx on a number of issues, still testified in a letter to Alexander Herzen that what he and Herzen were writing about "resembles a neat sketch drawn on paper, whereas Marx's judgment upon these events [European upheavals] is as it were engraved with iron force in the rock of time" (Paraphrased by George Lichtheim, A Short History of Socialism, 1971 p. 80).

Hess's Rome and Jerusalem: The Last National Question went unnoticed in his time, as most German Jews preferred cultural assimilation.

When Theodor Herzl first read Rome and Jerusalem he wrote that "since Spinoza, Jewry had no bigger thinker than this forgotten Moses Hess."

Vladimir Ze'ev Jabotinsky honored Hess in The Jewish Legion in the World War as one of the people that made the Balfour declaration possible, along with Herzl, Walter Rothschild and Leon Pinsker.