The latest book by Russian philosopher Sergey Mareev consists of two parts: recollections of his teacher Evald Ilyenkov, and reflections on some of the key themes of Ilyenkov’s philosophical heritage. The author traces several polemical lines related to the problem of the ideal, dialectics of the abstract and the concrete, the principle of historicism, as well as Ilyenkov’s interpretation of Spinoza and Hegel.