He began a life of great mortification. Ordained a priest in 1328, he studied in Paris and Avignon, and on his return became the Apostle of Florence, and Prior of his convent there. In 1360 he was consecrated Bishop of Fiesole, near Florence, and gained a great reputation as a peacemaker between rival political factions and for his love of the poor. He was also named papal nuncio to Bologna, where he pacified dissenting factions and won the hearts of the nobility with whom he was associating. He wrought many miracles of healing and conversion during his lifetime.
At the age of 71, while he was celebrating the midnight Mass of Christmas, the Blessed Virgin appeared to him and told him he would leave this world on the feast of the Epiphany, to meet the beloved Master he had served so faithfully. In effect, he died on that day in 1373, in the thirteenth year of his episcopacy. Miracles were so multiplied thereafter that Pope Eugenius IV permitted a public cult immediately. The city of Florence has always invoked him with confidence and happy results. He was canonized in 1629.
He is often represented holding his crosier, with a wolf and a lamb at his feet, or hovering over a battlefield on a cloud or a white steed – this in memory of his miraculous intervention in a battle the Florentine people won by his assistance.