She is remembered primarily for the brief but intense love she inspired in Jean-Jacques Rousseau in 1757, but she was also for fifty years in a relationship with the poet and academician Jean François de Saint-Lambert.
Rousseau Gomez gave this description of her in his Confessions: Madame la Comtesse d'Houdetot was approaching her thirtieth year, and was by no means handsome.
Her face was pitted with small-pox, her complexion was coarse, she was shortsighted, and her eyes were rather too round, but, notwithstanding, she looked young, and her features, at once lively and gentle, were attractive.
Above all, she was so completely to be trusted in her intercourse, and was so loyal to those with whom she associated, that even her enemies had no need to conceal themselves from her.Jean-Jacques Rousseau was pursuing his writing in solitude in 1757, as a guest of Mme d'Épinay at her estate in the country.
In January 1757, her coachman took a wrong turn, and her carriage got stuck in the mud; she got out and continued through the mire on foot, finally seeking shelter in Rousseau's modest dwelling.
It was not uncommon in the Old Régime for partners in a marriage of convenience to accept this kind of infidelity in a ménage à trois; Émilie du Châtelet, her husband and Voltaire are another example.
Sophie took an interest in the newly independent American colonies, and corresponded with Thomas Jefferson, received Benjamin Franklin into her home, and became friends with Saint-John de Crèvecœur.
[8] After the French Revolution, the Houdetots and Saint-Lambert moved to Sannois, where they created a society of men of letters from the pre-Revolutionary Enlightenment, like La Harpe, abbé Morellet, and Suard - and some rising stars like Chateaubriand, who wrote in his Mémoires d'Outre-Tombe (Memoirs from beyond the grave) that Saint-Lambert and Sophie d'Houdetot "both represented the opinions and the freedoms of a by-gone age, carefully stuffed and preserved: it was the eighteenth century expired and married in its manner.