According to the writings of some medieval theologians, one of painting's key purposes was to illustrate sacred texts for the largely illiterate population. This panel fulfills that aim, portraying the legend of Catherine of Alexandria in a dozen scenes. In fact, a painting of the Virgin and Child inspired Catherine's own conversion to Christianity. That event's depiction (at top left) is a fitting demonstration of the instructive power of medieval images.
The central panel of this altarpiece depicts Saint Catherine, Princess of Alexandria, holding her attributes of a book and martyr's palm. Catherine was of noble birth and well educated in the liberal arts. The narrative scenes begin at top left and portray the young Catherine and her mother visiting a holy hermit who gives the girl an image of the Virgin and Child, Catherine's vision of the Virgin and Child, her baptism, her mystical marriage to the Christ Child, her famous debate with pagan scholars, and the scholars' subsequent martyrdom after she converts them to Christianity. The episodes at the right include her imprisonment by the Emperor, the Empress's visit and conversion, her miraculous survival of death by a spiked wheel, the decapitation of the soldiers she converted to Christianity, and, lastly, her death by beheading.