The near-total suppression of Edward Conze’s ‘The Principle of Contradiction’ by the Nazi regime was a huge loss to 20th Century Marxist scholarship. Holger Heine’s discovery of a rare copy of the German manuscript, and production of an English translation, is undoubtedly one of the great gains of the 21st. There is much in the work to interest Marxists of course, but it also makes contributions that are of significance to all scholars of contemporary Philosophy of Logic. Moreover, anyone with an interest in the history of radical thought will find much food for thought within its pages, particularly in Heine’s excellent introduction. The work itself is a tremendously thorough investigation of the notion and nature of contradiction, and the different purported logical, metaphysical, psychological, and social principles that had (at his time of writing) historically been taken to govern it. Simply for this reason, the book should be of interest to anyone working in the philosophy and history of logic, quite regardless of their own theoretical tradition, or opinion of Conze’s.... Heine has achieved something truly wonderful with this translation. He has made available for study an early yet insightful text from a truly great thinker. Its contents resonate with, and bring together, many themes of contemporary thinkers. For the English-speaking academy to lose it to totalitarianism would have been an intellectual tragedy; to now have it available is an intellectual triumph.