The aim of the nineteenth-century volume of the Cambridge History of Political Thought is to provide a systematic and up-to-date scholarly account of the development of the central themes of political and social thinking in the century following the French Revolution. Its purpose is not to reinforce a canon but rather to trace the emergence of particular preoccupations and to delineate the development of distinctive forms and languages of political thinking. As in the preceding volumes, the aim will be to analyse the provenance and character of leading political ideas, to relate them to the specific historical contexts within which they arose and to examine the circumstances in which their influence made itself felt. This thematic approach has many advantages. But we do not consider it appropriate in every case. In a few instances – those of Hegel, Marx, Bentham and Mill – we have largely devoted chapters to a single author. For in assessing such major thinkers, whose influence and reputations have reached down to the present, we have considered it important that readers be enabled to evaluate their work as a whole.