Giotto painted this image of St. Paul in fresco, directly onto the wall of the Basilica of Saint Francis of Assisi. Fresco is a demanding technique. Earth pigments are mixed only with water, and then applied to wet plaster. This means the artist must work quickly, completing each section before the plaster dries. Look closely, and you'll see the join lines between these sections. The fresco medium dictates the aesthetic. The colors are muted, mineral. The image has a permanence, as it is literally part of the architecture. Yet within these constraints, Giotto achieved a remarkable naturalism. St. Paul emerges as a palpable human presence. The value of this work resides not only in its visual qualities, but also in the skill and labor involved in its production, and its integration with the sacred space. It challenges us to consider the many forms of expertise that contribute to the creation of art.