Although Isaiah Berlin liked to say that he left philosophy for the history of ideas after the Second World War, there is a decided continuity between his more purely philosophical writings, most of which are collected in this volume, and the more historical work for which he is better known. Included here are Berlin's early arguments against logical positivism and later essays which more evidently reflect his life-long interest in political theory, intellectual history and the philosophy of history. In two related pieces he gives his view on the philosopher's task, to uncover the various models - the concepts and categories - that we bring to our experience, and that help to form it. In his own words 'The goal of philosophy is always the same, to assist men to understand themselves and thus operate in the open, and not wildly, in the dark.'