 There are many editions of Mill’s more popular and influential works, including many of his writings in moral and political philosophy. The definitive edition of Mill’s writings is Collected Works of John Stuart Mill [CW], 33 volumes, ed. J. Robson (Toronto: University of Toronto Press, 1965–91) and  available online through the Liberty Fund.  In order to facilitate common reference among readers using different editions of his most commonly read texts—Utilitarianism, On Liberty, A System of Logic, and Principles of Political Economy—I will refer to those works using natural divisions in his texts, such as chapter, section, and/or paragraph. Otherwise, I will refer to Mill’s works using pagination in his Collected Works. I refer to the following works, employing the associated abbreviations.