One of Adam Smith's earliest writings, a letter to the Edinburgh Review published in 1756, concludes with an extended analysis of Jean-Jacques Rousseau's recently released Discourse on Inequality (see Letter: 250–4). Much of Smith's review is dedicated to highlighting a number of unexpected parallels between Rousseau and Bernard Mandeville, the notorious defender of commercial vice. After praising Rousseau's writing style in fulsome terms, Smith's appraisal culminates in the claim that ‘it is by the help of this style, together with a little philosophical chemistry, that the principles and ideas of the profligate Mandeville seem in [Rousseau] to have all the purity and sublimity of the morals of Plato, and to be only the true spirit of a republican carried a little too far’ (Letter: 251). I have argued elsewhere that the curious phrase ‘philosophical chemistry’ is an implicit reference to Rousseau's fundamental doctrine of the natural goodness of humanity, meaning both that human beings are naturally well-ordered, self-sufficient and hence happy (they are good for themselves), and that they naturally have little inclination or reason to harm other people and are averse to seeing them suffer (they are good for others) (see Rasmussen 2008: 64–6). I did not examine the last part of Smith's statement – that is, his reference to Rousseau embodying ‘the true spirit of a republican carried a little too far’ – mostly, I confess, because of its manifest ambiguity. The term ‘republican’ had a host of meanings in the eighteenth century, as it does today. Thus, it is not immediately clear what Smith meant by ‘the true spirit of a republican’, or in what sense he thought Rousseau carried this spirit too far. The present chapter rectifies the omission in my earlier discussion by exploring these questions. Along the way, it also considers Smith's and Rousseau's conceptions of liberty, arguing that their views are nearly diametrically opposed, but not (only) in the way that is generally assumed.