--
"I am the light of the world" proclaims Christ in St. John's Gospel. Between that claim, which has been commented at length by theologians and mystics, and the humble gestures performed by clerics and pilgrims, there exists a fundamental relation that historians have always ignored. Catherine Vincent studies this relation, basing her work on testimonies of religious life at the close of the Middle Ages. Rejected by the Reform, the usage of luminous signs and symbols (torches, candles, tapers, lamps, stained glass...) plays an important role in the practice of the Catholic faith (processions, liturgy, sacraments, cults of the saints) and reveals a fascinating religious anthropology.