John Stuart Mill (1806-73), son of a well-known political economist and philosopher, James Mill, was one of the formative influences of the nineteenth century. The works by which he is now best known, his essay on Liberty, published in 1859, his Representative Government, published in 1861, and the two volumes of Dissertations and Discussions, and his Autobiography, remain among the reading which is essential to the full understanding of the age in which Mill lived. Mr Cranston in this essay analyses and appraises the central arguments of Mill's chief works and suggests why Mill should continue to command attention and respect. Mr Cranston is the author of Freedom: a New Analysis (1953), Human Rights (1962), and the standard biography of John Locke (1957). He was Reader in Political Science at the London School of Economics, and later Professor of Political Theory at the European University Institute in Florence.