These essays, written in the 1930s and 1940s, represent a first selection in English from the major work of the founder of the famous Institute for Social Research in Frankfurt. Horkheimer's writings are essential to an understanding of the intellectual background of the New Left and the to much current social-philosophical thought, including the work of Herbert Marcuse. Apart from their historical significance and even from their scholarly eminence, these essays contain an immediate relevance only now becoming fully recognized.