The monumental figure of a seated saint, whose mitre identifies him as a bishop, was first sketched in grey pencil, which was then partially rubbed into the paper. For the second stage, Perugino used a brush to apply the delicate shading to the saint’s robe, the dark areas of his cloak, and then along the precise contours of the troughs formed by the folds. A needle was then used to pierce holes around the outlines and the essential internal structure to ensure the image could be transferred in a consistent manner. The relatively large format and the simplified style of executuion seem to suggest that the work served as a cartoon for use in a glass painting for a window. Perugino, the dominant figure of the 15th century Umbrian school and teacher to Raphael, was indeed primarily engaged during the 1480s in window design. A reconstructed design, made by completing the course of the gently curved stripes inside the aureole in order to form the cornice of an alcove, bears direct comparison with the windows that once featured at the monastery of S. Francesco de’ Conventuali in the Colle di Val d’Else.