Typically evaluated for the merits or otherwise of his famous account of 'value pluralism', Isaiah Berlin's more general political thought is less often discussed. However, broader reflection sheds light on three crucial elements necessary for a proper understanding of Berlin's work. First, it shows the importance and context of his analysis of Marx and Marxism in providing the basis for his distinction between pluralism and monism. Secondly, through his criticisms of Marxism, Berlin's political sympathy for a moderate nationalism, something also reflected in his personal considerations regarding Jewish identity, can more easily be gauged. Thirdly, and in conclusion, a combination of this political preference and the 'pluralism-monism' dichotomy offers an explanation as to why Berlin wrote the history of political ideas as he did.