The book focuses on a leading figure in the Church of the twelfth century, Atto abbot of the Benedictine Vallombrosan order and bishop of Pistoia, who was part of the entourage of Pope Innocent II. He was a promoter of the spread of Vallombrosan monks in central-northern Italy, Sardinia and Corsica, and promoted the cult of the apostle James Major by making him the patron saint of the city of Pistoia. This work, multidisciplinary in nature, brings together historical, historical-artistic and anthropological evidence on the life of this prelate and the religious and political context in which he operated, showing his sphere of action, which extended to the entire Western Mediterranean basin, as well as the vast network of contacts that, as a man of the Church and government, hagiographer and patron, he was able to effectively weave.