This volume is the concrete result of the seminars that took place in Arsago Seprio with the aim of commemorating the millennial of the death of the Bishop of Milan Arnolfo (998-1018) who, born in Arsago, drew from this village rich in traditions and culture his first cultural and religious addresses. Numerous themes of interdisciplinary research unfold around him, intended primarily to trace the origin and development of this important Roman vicus first and then an early medieval settlement, of which numerous archaeological remains remain. Secondly, to reconstruct the origins of the Pieve di San Vittore with the annexed Baptistery of San Giovanni, mentioned in a document of 1050, but certainly dating back to the early Middle Ages, if not even to the early Christian period. The parish center, as documents of the ninth century show, extended its jurisdiction over a large part of the inhabited centers dependent on the territorial district of Seprio, creating a link with the Lombard power center of greater importance in western Lombardy. The early medieval parish maintained a central role for a long period, undergoing an inevitable decline with the rise of the Visconti family (XNUMXth-XNUMXth century), which chose its place of residence in nearby Somma Lombardo. Arnolfo II, a man of strong personality, marks the moment of greatest vigor of Arsago, coinciding chronologically almost with the construction of the Romanesque parish complex, which still today constitutes one of the most important religious nuclei of the Lombard Romanesque, modified several times to meet renewal liturgical practices and recently restored. Restorations that are summarized here and accompanied by a very clear essay that invites not to restore but to proceed with careful and constant maintenance, less expensive but more useful for the conservation of historic buildings. Bishop Arnolfo had a rich and complex personality. He was a man of religion and culture, who is accompanied by the creations of important secular and religious volumes, including the famous Prayer Book, here analyzed with rigor in its artistic characteristics, which refer to specific stylistic or " school". But he was also a man of power, aware of the importance of the "political" alliances that were intertwined in the struggles for succession at the top of the empire. It is no coincidence that he acted in Milan, an ambitious and "top" city, of which he was undoubtedly a controversial but representative interpreter, while behind him his successor the charismatic Ariberto moved. The volume is completed with a study that investigates the complexity of the religious culture of the time on a European scale: the disputes, the interpretative and human doubts, due to the encounter between religious of different backgrounds. Here we meet the monk Anselmo di Aosta, of lay culture, who entered the monastery analyzes the relationship between knowledge and faith, as for him to believe is the way to know. In this dilemma between intellect and faith, sensibility and acumen are still present today.