An interdisciplinary analysis of Diderot’s short story, or essay, "Regrets sur ma vieille robe de chambre" (1769), this lecture aims to understand why Diderot chose to develop his critique of luxury (if such it is) in the context of what purports to be a short piece of life-writing, circulated to an elite readership via the Correspondance littéraire. As an art historian I am interested in accounting for Diderot’s use of both spatial form and ekphrasis to describe the appearance, and justify the possession of, luxury objects, a marine painting by Claude-Joseph Vernet most especially. However, the lecture will also engage with the moral questions raised in the discourse on the causes and effects of luxury, and proposes Michel Foucault’s theory of practical ethics as the appropriate model for the interpretation of Diderot’s apparent ambivalence with regard to non-essential consumer spending. The figure of the philosophe is here analysed in the context of the mid-century debate about the political morality of ‘his’ assimilation into elite salon culture, and in contrast to the much reviled figure of the amateur. This lecture addresses the relation between public and private in the specific contexts of the open door of hospitality on the one hand, and, on the other, of the materiality, or persuasive pleasure of the literary text.