In tribute to their master whose scientific work has profoundly renewed the history of Western Christianity in the Middle Ages, students from André Vauchez, a member of the Academy, wanted to offer him the 24 studies gathered in this volume. Rooted in the main thrust of the discussion which he conveyed to them and which they in turn developed, they were grouped into five themes, on the basis of which spiritual experiences were so many quest for perfection. The opening of Jean DELUMEAU, a member of the AIBL, dedicated to the replenishment of the mystic Agneau of the Van Eyck brothers introduced a first set of texts devoted to hagiography and saintness, which were extended by an exploration of the places where the worship of the Holy worship had taken root. Then, the channels of dissent come, followed by the new expression of the norm, conveyed by the leading orders, before various ways of religious practice and its engagement in the century are discussed. A epilogue puts André Vauchez’s thinking in perspective with that of Alphonse Dupront, before the conclusion of Nicole Bériou, the correspondent of the AIBL. With an index, the book also includes the bibliography of André Vauchez’s work.