In Chapter 12 of I. S. Turgenev's Fathers and Sons, a progressive official is described as being like the statesmen of the Alexandrine era, who, “getting ready for a soiree at M-me Swetchine's, who dwelled at that time in St Petersburg, read a page from Condillac”. Various editions of Turgenev's novel provide commentaries on both Sophie Swetchine (a Russian Catholic) and Condillac (a French philosopher, deist and sensualist). Yet no explanation is given concerning why statesmen, in preparation for a visit to a Catholic, would need to read a sensualist philosopher instead of, say, some work of theology. The two names and the two persons are commented upon separately, while, if their relationship is analyzed, it becomes obvious that an important link is missing from this fragment. This paper attempts to uncover this missing link, which proves to be Joseph de Maistre, Sardinian emissary in Russia and French religious thinker. A memoir source mentions that Pavel Dmitrievich Kiselev, later on a prominent minister during the reign of Nicholas I, used to visit Mme Swetchine's salon and talk to de Maistre at the instigation of his friends, who also made him read a few chapters from Condillac beforehand. Discussing Condillac with the hostess was pointless; but this was not the case with de Maistre, who in his writings routinely disputed with the French sensualist, and whose demeanor suggested that he needed to be challenged to engage in an eloquent monologue. The story of Kiselev reading Condillac prior to visiting Swetchine's salon and talking to de Maistre comes from Prince P. V. Dolgoruky, who used to meet Turgenev frequently in Paris, just when Fathers and Sons was still a work in progress. Therefore, it is entirely possible that Turgenev could have heard this story. But both de Maistre and Swetchine were water under the bridge for him, so he did not hesitate to skip the missing link and paid no attention to the paradoxical nature of what was left — a construct in which, to worm oneself into Swetchine's favor, one has to boast about one's mastery of Condillac's writings.