Clement Greenberg (1909-1994) was a colossus of twentieth-century American art, achieving a degree of authority almost unimaginable for a critic today. For more than thirty years he was both lionized as a proponent of formalism and criticized for his perceived dogmatism. In the postwar period Greenberg used his position of influence to advocate the importance of abstract expressionism and color-field painting and to establish the careers of such artists...