Mill’s range of interests was remarkably wide, extending from education and psychology in his two-volume Analysis of the Phenomena of the Human Mind (1829a), to political economy (he persuaded his friend David Ricardo to write on that subject, as Mill himself did in his Elements of Political Economy, 1821), to penology and prison reform, to the law and history, and, not least, to political philosophy. On these and other subjects he wrote five books and more than a thousand essays and reviews. It is with Mill the political philosopher and educational theorist that the present article is principally concerned.