Italian theologian and presbyter of the Diocese of Milan, he obtained a doctorate in theology and taught as professor of systematic theology and history of medieval theology at the Theological Faculty of Northern Italy in Milan; he was a professor of the same subjects at the Faculty of Theology of Lugano, where he directs the Institute of the History of Theology, which he founded. He is a member of the Pontifical Academy of St. Thomas Aquinas and of the Pontifical Academy of Theology; he is associate doctor of the Ambrosiana Library. He chairs the Institute for the History of Medieval Theology in Milan and directs, in collaboration, the series Library of Medieval Culture and Medieval Heritage. History of theology from Boethius to Erasmus of Rotterdam at the Jaca Book publisher. In the medieval field he is the author of numerous volumes on theologians of the eleventh, twelfth and thirteenth centuries; he collaborated on the Italian Opera Omnia (Latin-Italian) edition of Sant'Ambrogio and edited, in collaboration, the Italian Opera Omnia (Latin-Italian) edition of Sant'Anselmo d'Aosta and the Colombanian Corpus. His areas of work are: Theological systematics (sacramental, ecclesiology and Mariology); history of medieval and modern theology; medieval monastic literature and theology; Dante's work; the liturgy, especially the Ambrosian liturgy, in whose reform he collaborated; history of the Ambrosian Church.