"Socialism ... is essentially prophetic Messianism ..." So Erich Fromm writes in his 1961 classic Marx's Concept of Man. World-renowned Critical Theorist, activist, psychoanalyst, and public Marxist intellectual, Erich Fromm (1900-1980) played a pivotal role in the early Frankfurt Institute for Social Research and influenced emancipatory projects in multiple disciplines. While he remains popularly well known as author of such best-selling books as Escape from Freedom and The Art of Loving, Fromm's contribution to Critical Theory is now being rediscovered. Fromm's work on messianism in the 1950s-1970s responded to earlier debates among early twentieth century German Jewish thinkers and radicals, including Hermann Cohen, Rosa Luxemburg, Martin Buber, Gershom Scholem, and Georg Lukács. The return to Fromm, as well as growing interest in Jewish messianism's influence on the Frankfurt School, makes this book timely. Fromm's bold defense of radical hope and trenchant critique of political catastrophism are more relevant than ever.