Dagron's inaugural lecture, delivered on January 30 1976, marked a paradigm shift and a significant evolution of the discipline towards anthropology. As knowledge of the Byzantine world progressed, Dagron confessed his difficulty in defining what " Byzance " consisted of, and his temptation to extend research beyond the traditional limits of the empire, beyond Greek-language sources. Starting from the double observation that the Byzantine Empire disappeared (in 1453), yet remains an essential presence in the definition of certain national identities (Russia, the Balkan countries and Greece), Dagron proposes a new approach and new tools. To this end, he borrows from the sociology of Georges Dumézil, appropriating the field of " ideas " : by dint of problematic, even dialectical schemes, Dagron aims to rise to the level of functions (of a ritual), logic (of behaviors), structure (of a political system) or presuppositions (of a social classification).

Dagron identifies several original systems of representation in the millennial history of Byzantium, providing touchstones for renewed cross-disciplinary studies. First , Dagron shows that Constantinople established one of the first systems of international relations, claiming two histories (New Rome and New Jerusalem) inherited from the Roman world, and imposing this vision on its neighbors : Rome versus Constantinople bipolarity and the unique legitimacy of imperial dignity ; one of the author's favourite subjects remains the capital, accompanying his thesis defended in 1968 with a supplement on imaginary Constantinople in 1984. The author's innovative approach, which blends reality with the representation we make of it, is based on a search for equivalences between concepts, and attempts to identify parallels between the icon as a trace of a model and numerous Byzantine intellectual fields (literature, architecture, ceremonial, liturgy), a further illustration of a conception in which form is of sacred origin and a source of truth. Finally, on the subject of Christianization, Dagron notes that Christianity went from being the exception to the rule between the^5th century and the end of iconoclasm, overturning the ancient organization and in turn becoming a ferment of tradition, even constitutive of a civilization riveted to its particularisms, to such a depth that the efforts to unite the Churches from the ^13th century onwards failed to achieve.

Ultimately, while Dagron refuses to look for a " Byzantine man " that never existed, he does contribute to the construction of an anthropology of Byzantium through thematic studies (e.g. death, the theme of his first-year course) that constitute " stratigraphic sections ", enabling us to catch a glimpse of a vanished yet highly original world.

Notice written by Marc Verdure (Collège de France - Institut des Civilisations).