As a philosopher grounded in Hegel, Marcuse has concerned himself with forms of thought; as a political radical he has sought to relate them to the material and emotional spheres. His work has two exceptional characteristics. It represents one of the few serious attempts at integrating and drastically revising Marx and Freud. And he has never hesitated to change his mind (as these early essays testify): the optimism in Eros and Civilization gave way to the bleak appraisal of One-Dimensional Man, then by last year his revolutionary hopes revived. Most of these essays were written in the Thirties ""before Auschwitz,"" as he says in the introduction, where he questions their immediate relevance, Indeed, they are for devotees, not dabblers, who will find his vocabulary fearsomely Teutonic and his topics (which include ""Industrialization and Capitalism."" ""The Struggle against Liberalism in the Totalitarian View of the State,"" ""Philosophy and Critical Theory,"" as well as ""On Hedonism"" and ""The Concept of Essence"" in a more traditional vein) formidably heavy. But philosophy students and New Leftists will pounce. Footnotes.