“How had they met ? By chance, like everybody else.” The incipit is famous, and places the narrative firmly under the control of the vagaries of chance. The situation is clear : everything, in Jacques the Fatalist, will be either interrupted or displaced, indefinitely differed. Which, as one might have guessed, is not without consequences for the reader. Taking the opposite line to a strictly structured narrative, explicitly refused by the author of Pensées sur l’interprétation de la nature (Thoughts on the Interpretation of Nature), Jacques the Fatalist stages an heuristic regime where what Diderot calls eccentricity, which must be understood, literally, as a care to take the unbeaten path, is given full freedom, in an exemplary survey of thought and knowledge which risks – or better said bets on – taking the wrong turn and thus both discovers and invents. The same insisting mode of writing, from the way the reader is lost in this “rhapsody of facts some real, others imaginary, written without grace and distribued without order”, to the wrong turns taken by a master and a Jacques ceaselessly brought back to the same enigmatic cross-roads, pervades the heart of the fiction and points to possible meanings both affirmed and subverted, multiple, polymorphous, constantly reinvented through a fiction which is all the more “true” that it gives itself as such, all the more perverse that it reveals its mechanisms, creating thereby another fiction, that of a new subject of knowledge, which constantly need to be reinvented.