One of the fundamental and perhaps one of the most important principles of Marxist-Leninist philosophy is the assumption that internal contradictions are inherent in all things and in all phenomena of Nature. "In its proper meaning', wrote Lenin, "dialectics is the study of the contradictions within the very essence of things'¹. The formulation and the context make it clear beyond any possible doubt that for Lenin there was nothing phenomenal (in the Kantian sense) about the contradictions; they are inherent in the Ding an sich.