This book shows that Max Horkheimer's program of critical theory and his research throughout his career as a university professor and thinker are rooted in the cogency of philosophical questions and an in-depth knowledge of the historical development of philosophical problems in their close correlation with the socio-economic framework which shaped the 'bourgeois society' and the Modern Era. Indeed, his analyses of modern philosophers allows us to understand how the bourgeoisie seeks legitimisation and consolidation of its position, partly through the voices of its thinkers. In this way, in his investigation of early modern philosophy problems, and through constant dialogue with his colleagues Adorno, Marcuse, Pollock and Fromm, Horkheimer expresses a profound awareness of the critical force inherent in thought which, admittedly, is ever vulnerable to crisis and weakening, but which can always be reactivated.