“The selection of entries arises from a double labor of exploration, both diachronic and synchronic. Diachrony allows us to reflect on crossings, transfers, and forks in the road: from Greek to Latin, from ancient Latin to scholastic then humanist Latin, with moments of interaction with a Jewish and an Arab tradition; from an ancient language to a vernacular; from one vernacular to another; from one tradition, system, or philosophical idiom to others; from one field of knowledge and disciplinary logic to others. In this way we reencounter the history of concepts, while marking out the turnings, fractures, and cariers that determine a “period.” Synchrony permits us to establish a state of play by surveying the present condition of national philosophical landscapes. We are confronted with the irreducibility of certain inventions and acts of forgetting: appearances without any equivalent, categories, false friends, intruders, doublings, empty contradictions, which register within a language the crystallization of themes and the specificity of an operation. We then wonder, on the basis of the modern works that are both the cause and the effect of the philosophical condition of a given language, why the terms we ordinarily consider as immediate equivalents have neither the same meaning nor the same field of application – what a thought can do in what a language can do.”