Saint Catherine of Alexandria stands among the shattered pieces of the spiked wheel upon which she was tortured, which miraculously broke during her ordeal. The sword she holds was the weapon that eventually killed her. It is covered with silver leaf, while the hilt and pommel are gilded. She is flanked by two of the Four Evangelists: Saint Matthew, whose symbol, the angel with its large curved wings, crouches by his feet, and Saint John the Evangelist, whose symbol of an eagle perches on a rock at his feet. Matthew, his head slightly bowed and eyes focused, is poised, pen in hand, to write the next chapter of his Gospel. John holds a golden chalice containing a tiny serpent, a reference to his survival after drinking poison.

This painting once formed the inner face of the left-hand shutter of an altarpiece (its central panel is now lost). The other shutter  (Wallraf-Richartz Museum, Cologne) shows Saints Mark and Luke with Saint Barbara. The Cologne panel is still in its original carved wooden setting, which has pointed arches and intricate tracery designs above and a more simple decorative frieze below. Our panel, which has been cut down at the top and bottom edges, would have been set in a similarly elaborate carved frame and then connected to the central panel. The central part may have been a carving, or another, larger painting with carved borders like Lochner's painting of the Adoration of the Kings in Cologne Cathedral.

The painting on the reverse of our panel -- its outer face -- is very damaged, but it shows Saints Jerome and Gregory the Great on either side of a female saint, possibly Saint Cordula. Cordula was a saint local to Cologne, one of the 1000 virgins martyred in the city with Saint Ursula. The reverse of the Cologne panel (now separated from the front but also in the Wallraf-Richartz Museum) shows Saints Ambrose, Cecilia and Augustine.

Both reverses also depict the altarpiece's patrons kneeling at the saints' feet. They are dressed in the robes of the religious group called the Order of Saint John of Jerusalem, its distinctive emblem of the spiked cross emblazoned on their sleeves. There was a church in Cologne belonging to the Order and dedicated to Saints John and Cordula; given the patrons' membership of the Order, it may have been made for one of the altars of this church. The six saints and two donors depicted on the outer faces would have been visible when the shutters were closed.

The vibrant colours of the saints’ robes are characteristic of fifteenth-century painting in Cologne. Lochner chose a selection of varied but complementary colours, and has united the figures through his use of them: John's red-lined mantle echoes the shadows of Catherine's robe, which is lined with a green that reflects the deepest shade of Matthew's drapery. The three-dimensionality of the figures is defined by the openings and fold of their draperies and they stand out like sculptural reliefs against the gilded background, which is decorated with a Renaissance 'pomegranate' pattern often found on textiles at the time. The pattern was created by carving small grooves in the chalk ground before placing gold leaf over the top. The indentations add texture to the image, particularly when lit by candlelight.

Style: Gothic, Early Renaissance, International Gothic