Clement Greenberg was one of the most influential art critics of the twentieth century, setting new standards on the American art scene of the 1950s and 1960s. The shift of the art world's epicenter from Paris to New York, where the contemporary art agenda was set after the Second World War, was in no small part a result of his efforts. Beginning in the 1970s, changing ideological, political, and aesthetic currents cast him in an ambivalent light, and he remains a polarizing figure today. His critical practice courted such controversy: he took positions in a brashly unapologetic tone that was often felt to brook no dissent. The present volume seeks to complicate this picture by initiating a fresh reading of his work that will revise long-established assessments. It presents previously unpublished texts by Greenberg that bring the art critic's thought processes and writing practice into focus. The typescripts reveal the painstaking labor that went into Greenberg's trademark concision. By publishing these documents complete with his subsequent corrections and modifications, the book lets the reader observe the critic at work backstage, in the privacy of his study, and illustrates that and how he shifted back and forth between subjective stances and the aspiration to objectivity and was always ready to rethink his positions. Both within and across the texts, he recognizably subjected his claims to ongoing critical interrogation. To read him as an author of dogmatic assertions is to underestimate his work and overlook the productive potential of his approach: Greenberg's bold claims served him as heuristic devices, as footholds that were by no means incontrovertible. Putting "criticism" in its literal sense into practice, he strove to mark differences and identify prospects for the evolution of the art of his time, fully aware that the stances he took onstage were particular and shaped by the historical moment. The texts collected here were written in a variety of contexts, and most of them reached only the limited public audiences of lecture halls; among them are the Gauss Seminars, which Greenberg delivered at Princeton University in 1958-59 before a number of intellectuals and artists who were or would go on to become prominent figures in American arts and letters. Among them were Hannah Arendt and Michael Fried, who recalls attending the lectures in his contribution to the present volume, one of the four essays that round out the book, analyzing the sources and embedding them in larger perspectives.