The article provides an anlytical description of manuscript Namur, Grand Séminaire 37, which contains the only witness of the Latin translation of Clement’s Letter to the Corinthians. While historiography has always dated the production of this codex generally to the eleventh century, palaeographical and codicological analysis enables a more precise dating in the years straddling the eleventh and the twelfth century. The production of this manuscript within this period, defined by Paul Fournier as "un tournant de l’histoire du droit", makes it a building block in the political and ecclesiastical construction of papal primacy in the Middle Ages.