Paul Lemerle's inaugural lecture, delivered on December 8 1967, constitutes the core of his research program. Choosing to call his chair History and Civilization of Byzantium, he naturally intends to cover the period from the foundation to the fall of Constantinople, covering the Byzantine area and occasionally extending into the West, Asia, the Slavic world and the world of Islam. However - and this is where his main originality lies - monuments of art, favoured until the 1960s by historians, occupy in his eyes an equivalent place to other witnesses to the past : texts, archival documents, inscriptions and coins.

Lemerle's work on sources calls for a metaphor on his part, that of looking at Byzantine history " from below ", i.e. an asceticism that progresses slowly, with difficulty, through the labyrinth of the humblest sources and documents to bring to light what ensured the Empire's millennial continuity. Paul Lemerle's  interests are manifold: man's relationship with the land and the agrarian economy, currency and its astonishing stability over the period, urban areas, trade, neighbourly relations with East and West, the symbolic and cultural field, the ^11th century as a turning point.

This emphasis on material sources is based on two observations. First , Byzantium was a state administered to a degree unmatched by any other medieval state, and this fact of civilization deserves to captivate the attention of the historian of Byzantium, who must aim for objective knowledge, without a priori. In passing, Paul Lemerle points out that this diversity of materials implies a collaboration of researchers around a place (a library) where working instruments and workers would be gathered. During his years at the Collège de France, Lemerle implemented what he describes as " rêve ", i.e. a library surrounded by sources (notably the Archives de l'Athos) and editorial activity gathered in the journal Travaux et mémoires.

Lemerle goes on to explain the need for a dual approach to this material source, taking into account both the world of signs and the world of forms : the historian must not be fooled by over-simplifications, for many influences and practices were mixed, accumulated, preserved or combined in the Byzantine world, and learning about complexity is a necessity for the Byzantinist. Paul Lemerle is particularly interested in the notion ofByzantine humanism, based on a fundamentally Hellenic culture (mingled with a fundamentally Christian morality) showing all the signs of an apparent immobility, but which nonetheless testifies to an astonishingly active participation in the affairs of the time. Immobilism as the image the Empire wished to project of itself, drawing on its Greco-Roman and Christian roots ; change whose techniques and means should be the subject of careful study (gestures, ritual, quotation, rhetoric).

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