The altarpiece is a hagiographic icon, a style of reredos in use until the thirteenth century which featured an image showing a full-length portrait of a saint or the Virgin Mary surrounded by a frame illustrating the stories of the featured person. This polyptych by Sienese artist Pietro Lorenzetti illustrates the life of Saint Humility (1226-1310), a noblewoman from Faenza who became a nun late in life and traveled to Florence to found a Vallumbrosan monastery. The saint is pictured wearing the habit of her religious order, holding a book and a palm leaf, a symbol of glory; her head is covered with sheepskin, an emblem of humility and an iconographic characteristic typical of Saint Humility. At the bottom left a woman is knelt in prayer, most likely representing the customer who commissioned the work. The stories surrounding the central image recount Saint Humility's life, from the moment she chooses to don the religious habit before her conversion, to the miracles she worked in the convent in Faenza, to her journey to Florence where, in 1282, she founded the monastery of San Giovanni Evangelista just outside the city wall's, until her death and funeral service presided over by the priest. The lively narrative of the scenes, set in architectural environments and landscapes which abound with realistic details, is clear and informative, reiterating the educational purpose that images played in an era when literacy was a skill known only to the few. The altarpiece has been broken up into parts and is currently missing the frame, two pinnacles and two of the story panels, the latter of which are exhibited in Berlin (Staatliche Museen, Gemäldegalerie). The piece remained in the church of San Giovanni Evangelista until around 1529, when the nuns had to abandon the convent while Florence was under siege by imperial troops. After moving numerous times, the Women of Faenza, as they were known, reached the monastery of San Salvi, bringing with them the most treasured furnishings of their original home; these included this representation of Saint Humility painted by Pietro Lorenzetti.