The top of the central light depicts Moses and Elijah on either side of the central figure of Isaiah. The appearance of Moses and Elijah together, especially in this panel above the central figure of the Crucified Christ, is a powerful reminder of the presence of these two central Old Testament figures with Christ at the Transfiguration. Both Moses and Elijah are mentioned in the Gospels more often than any other Old Testament figures.
Moses lived in the 13th century BC and is depicted here as an old man, carrying the Book of the Law. Moses is of central importance in the Hebrew tradition, where he is seen as the original lawgiver, the visionary leader, the deliverer of his people, and as a prophet who had spoken directly with God. The Law of Moses was a defining characteristic of the Israelites, and the mission of Jesus is seen as both fulfilling and transcending this law.
Elijah is a different, and probably even more charismatic figure in the popular mind of the time. He lived in the 9th century, BC, and was the most wonderful prophet of the Old Testament. He is depicted here as a younger man, with his hand raised as a blessing, or as a warning. He undoubtedly presented as a somewhat wild and colourful figure, wearing a garment made of hair with a leather girdle, living in caves and clefts in the mountains, and appearing swiftly and leaving as quickly. He came to denounce the apostacy of Israel and to prohesy a long drought in the land. There are stories of miraculous feedings and of the restoration to life of the child of the widow who gave him shelter.
Elijah challenged the prophets of the nature god Baal, and demonstrated the power of Yahweh by the miraculous lighting of the sacrifical pyre and the ending of the drought. According to the legend, Elijah went up to heaven in a whirwind, and his return will herald the final days. Many other legendary tales are associated with the prophet's memory, and Carmelite monks have long cherished the belief that their order could be traced back to Elijah, whom they hailed as their founder.
The central figure in this panel is Isaiah, who is depicted as a stately figure in priestly robes, reading from a scroll. Whether the Book of the Prophet Isaiah is the work of several people, or of one, Isaiah stands out in the latter part of the 8th century BC as one who was deeply concerned about the politics of his time, with a strong sense of religious duty and of social justice. God is shown as the avenger of disregarded human justice as much as of His Divine rights; he cannot, and will not, let injustice, crime and idolatory go unpunished, and the Assyrians were to be seen as the means appointed by God to level the pride and tyranny of the corrupt rulers.
Isaiah's name is not associated with the performance of miracles, as are the names of Moses and Elijah. Rather, Isaiah is seen as the greatest of the literary prophets. His poetical genius is unsurpassed in the descriptive, lyric and elegaic forms. His compositions have an uncommon elevation and majesty of conception, a wealth of imagery, and an adherence to propriety, elegance and dignity. These characteristics are nowhere more apparent or powerful than in the Songs of the Suffering Servant in the second part of the Book of Isaiah. Christian tradition has always applied this vision to the sufferings of Christ in his crucifixion.