Joseph Butler, Stephen L. Darwall (1983). “Five Sermons, Preached at the Rolls Chapel and A Dissertation Upon the Nature of Virtue”, p.47, Hackett Publishing
Joseph Butler (1856). “The Analogy of Religion, Natural and Revealed, to the Constitution and Course of Nature: To which are Added, Two Brief Dissertations: on Personal Identity, and on the Nature of Virtue; and Fifteen Sermons”, p.490
Joseph Butler, Stephen L. Darwall (1983). “Five Sermons, Preached at the Rolls Chapel and A Dissertation Upon the Nature of Virtue”, p.48, Hackett Publishing
Joseph Butler (1856). “The analogy of religion, natural and revealed, to the constitution and course of nature: to which are added, two brief dissertations : On personal identity, and On the nature of virtue; and fifteen sermons”, p.432