It may seem paradoxical to speak of the incommensurable in Claude Simon when readers appear to have found considerable common ground for discussing his oeuvre. Numerous studies have treated the continued emergence of the workings of memory, the new realms of family history, the places of history, and the relationship of all these to his writing's dynamics. While these aspects of his work solicit consensus, the broader question of a sensus communis and the critical issue of incommensurability remain unexamined, out of harmony with the themes of correspondence, proximity, continuity and unity in Simon criticism. I do not wish, however, to revive critical debates in which rigid oppositions prevailed between representation and textuality, referentiality and literarity, and history and writing, oppositions which, with superb irony, have in any case become the material of fiction in the quotations in Le Jardin des Plantes (pp. 355–58) from the Cerisy colloquium proceedings. Rather, I propose to focus on occurrences in a variety of contexts that may be read as emblematic of Simon's writing. These occurrences all involve incidents of collision, accident, encounter and shock. The word incident itself, from incidere (Lat.), to come upon, happen and fall upon, evokes a range of associations having to do with encounter, the incidental and the event of the singular. These incidents may be examined not only in terms of narrative discontinuity and fragmentation, but also in relation to a broader crisis of commensurability haunting the twentieth century's end and promising to engage us well into the twenty-first. Many literary and cultural critics talk of ‘sites’, implying that spaces, histories and symbolic systems are not unquestionably held in common, and that their very uncertainty requires that they be laid out, measured and charted. Sites are instituted as cultural spaces, despite or due to the absence of a common standard of measurement for mapping their edges and distance with respect to one another.