Diderot, d’Alembert, Rousseau, Condorcet, Grimm, Boulanger, Buffon, Beccaria and Lagrange all regularly attended d’Holbach’s intellectual salon. Gibbon, Hume, Garrick, Sterne, Walpole, Smith, Priestley and Franklin were among his anglophone friends and associates. D’Holbach maintained this intellectual and reformist côterie of friends for 30 years, an impressive feat not only for the level and international breadth of discourse, but because he and his circle were so frequently critics of established society. He not only wrote for Diderot and d’Alembert’s Encyclopédie, but also helped fund it.
Hutcheson taught him, while Hume knew him from Smith’s professorship in Glasgow (they became best friends). Adam, Black, Stewart and Hutton were members of Smith’s weekly ‘Oyster Club’ in Edinburgh. Helvétius and d’Alembert were met at d’Holbach’s intellectual/libertarian salon in Paris, as was Turgot (who may have given Smith some of his economic ideas there). Johnson and he repelled each other, Bentham and Rochefoucauld corresponded with him, while Quesnay was credited in his ‘Wealth of Nations’. He met Voltaire when he spent 2 months in Switzerland, and visited Smollett when Smollett visited Edinburgh.
Hume resigned his librarianship in favour of Ferguson, but alone thought his magnum opus ill-advised. Ferguson met Voltaire while travelling in Europe (his friends Hume and Adam meanwhile covering his back in Edinburgh). Gibbon wrote to him praising their mutual friend Smith’s ‘Wealth of Nations’, and his relative Black sold him his house. Hutton was among the Scottish Enlightenment circle gathered in Edinburgh, a member (with Ferguson, Hume, Smith, Black and others) of the influential ‘Poker Club.’ Ferguson was among those who lionised Burns (who met the young Scott in Ferguson’s house, a regular meeting-place for Edinburgh literati).