These two notebooks were discovered while Philip Pomper was doing research at Harvard’s Russian Research Center for a book on Trotsky, Lenin and Stalin after the Russian Revolution and were published by Columbia University for the first time in 1986. They present fascinating new insights into Trotsky’s philosophy, politics, and psychology and this volume is a significant addition to an understanding of his revolutionary career. They shed new light on his relationship to Lenin and Bolshevism, his criticism of dialectics and Darwin evolutionism, and his reflections of Freudian psychology as he ponders the relationship of the unconscious mind to the philosophical issues surrounding dialectics. The original Russian text of the notebooks, prepared and annotated by Felshtinsky, is also presented here to make the material available to readers of Russian.