Saint Vincent Panels

The Saint Vincent Panels, or the "Adoration of Saint Vincent" panels, are a polyptych consisting of six panels that were perhaps painted in the 1450s. They are attributed to the Portuguese painter Nuno Gonçalves, who was active from 1450 to 1471. Traditionally, the polyptych is dated to the 1450s due to the putative prominence of Prince Henry the Navigator among the persons represented in the panels (Henry died in 1460). Controversy concerning the true nature of Henry's presence in the panels - if any - along with the inclusion of figures that can be identified as his brothers, all of whom died before 1450, renders it difficult to assign any secure date for the creation of the panels other than sometime during the "floruit" of the painter Gonçalves.
The original retable, during its stay in the Cathedral of Lisbon, contained "over twelve" panels, as a source from 1767 states. They were displayed in the cathedral at least until 1690 and were set aside in the cathedral until 1742. They were then transferred to the palace of Mitra, where they escaped the devastating earthquake of Lisbon in 1755.
The panels are now housed in the Museu Nacional de Arte Antiga (National Museum of Antique Art), in Lisbon, Portugal.
Discovery.
Found during the late 1880s in the monastery of Saint Vicente de Fora in Lisbon, the panels depict scenes associated with the veneration of Saint Vincent of Saragossa. This polyptych consists of six separate panels of oak painted with oil or tempera.
The only reference that art historians can use to support the attribution of the creation of the panels to the painter Gonçalves was written in the 16th century by Francisco de Holanda. The reference mentions a great work of art made by him that is inferred to be these panels. There has also been speculation that the father of Hugo van der Goes collaborated in the painting of the panels, but no firm evidence to support this hypothesis exists. In any case, the "Saint Vincent Panels" are regarded as the greatest achievement of pre-modern Portuguese art.
Interpretations.
Since their discovery in the late 19th century, there has been a continuing dispute over the identity of the painter and the subjects portrayed on the panels. Some basic questions, still unanswered, are these:
The majority of experts who have studied this polyptych agree that the panels display several social groups of 15th-century Portugal. They also agree that the children of King John I are represented on these panels, but there is disagreement about their placement and identity. 
Panel of the Prince: alternative hypothesis.
One of the more controversial issues concerning the panels is the depiction of Prince Henry the Navigator. At first glance, the appearance of the man in black in the third panel is quite compatible with traditional conceptions of Prince Henry's likeness: a man with a light moustache and distinctive black round chaperon such as can be found in numerous representations today. However, there are strong reasons to doubt that this is him.
The most basic problem in identifying the man-in-the-chaperon in the Saint Vincent Panels derives from the lack of confirmed portraits of Prince Henry that date from his lifetime. The only other 15th-century image of the man-in-the-chaperon is found in the frontispiece of a copy (currently held by the Bibliothèque nationale de France) of Gomes Eanes de Zurara's "Crónicas dos Feitos de Guiné", written in 1453. Zurara's book is an account of the early Portuguese discoveries in Africa along with a hagiography of Prince Henry, to whom the author assigned singular credit for the discoveries. As a result, it has been assumed that the frontispiece depicts Henry, especially since the motto underneath it seems to have been Henry's own.
One alternative hypothesis postulates that the man-in-the-chaperon in Zurara's book might actually be King Edward of Portugal (r. 1431-38), Prince Henry's brother. It has been pointed out that critical phases of the discoveries were launched during his reign, and it would not be unusual for a portrait of a king to adorn a chronicle of events that occurred during his reign.
This alternative hypothesis can be used to help clarify the identity of the figures surrounding St. Vincent in the Panel of the Prince. Specifically, it offers an explanation for the symmetrical arrangement of men and women as pairings of kings and queens. In this interpretation, the standing pair would be King Edward (in a black chaperon), standing at the right and balanced on the left by his wife, Queen Eleanor of Aragon. Below them would be their son, King Afonso V of Portugal, kneeling on the right and facing his consort, Queen Isabella of Coimbra, who is kneeling on the left. The boy in the panel would then be Edward's heir, the future King John II of Portugal.
This alternative hypothesis seems more logical than the original hypothesis that insists on identifying the man-in-the-chaperon as Prince Henry. Since Henry was a bachelor, it is not obvious what woman would be suitable to pair with him as the standing figure on the left. His closest female relatives were his mother Philippa and sister, Isabella, Duchess of Burgundy, both of whom would be more properly paired with their husbands. Moreover, Isabella did not live in Portugal after 1430, thus her lack of involvement with Portuguese society at the time the panel was painted would probably disqualify her from inclusion. If the uncle of a king were to be incorporated in the panel, it would more properly be Peter, Duke of Coimbra, who was once the regent of Afonso V and the father of his bride.
Another interpretation of the figures includes Henry in the panel, but proposes Edward as the kneeling king and Afonso V as the boy. Regardless, all traditional means of explaining Henry's presence in the panel strike one as forced, formulated simply to accommodate a preconceived notion that Henry must be the man-in-the-chaperon. Since Edward was the brother of Henry, it is perfectly possible that he bore a close enough resemblance to Henry that the traditional identification in the Zurara book is perfectly correct, and that Edward's appearance in the panel is only coincidentally similar to what is depicted for Henry in the Zurara book.
The alternative hypothesis with King Edward as the man-in-the-chaperon is more logical; pairs of kings and queens are all that are featured in the panel, with no intrusion from other family members, except for the minor son of one of the royal pairs. Other relatives are featured in a panel of their own (see below). In consideration of this, the Panel of the Prince perhaps ought to be called the Panel of Kings instead, with the king intended to be featured most prominently apparently Afonso V, who was the reigning king of Portugal throughout the "floruit" of Nuno Gonçalves, thus the most likely candidate as patron for the preparation of the panels.
Panel of the Knights: alternative hypothesis.
Hypotheses that assert Henry the Navigator is not the man-in-the-chaperon identify him in another panel: the fifth panel known as the "Panel of the Knights". This alternative interpretation posits that the four knights featured in the panel are the four younger brothers of King Edward of Portugal, as follows:
There has also been much discussion around the possible political significances of this panel. It seems, in particular, that by the poses, this panel aims to humiliate Henry the Navigator, possibly for allying himself with Afonso of Braganza against his full brother Peter, Duke of Coimbra, in the Battle of Alfarrobeira in 1449. These features of the portrait have been noted: 
It is worth remarking that the colors chosen for the princes seem to match the liturgical colors of the Roman rite—black (Ferdinand) for mourning of the dead, green (Peter) for ordinary, red (John) for passion and sacrifice and purple (Henry) for penance and mortification.
If this interpretation is valid, then the polyptych of St. Vincent may very well have been conceived by Nuno Gonçalves as a piece of anti-Braganza political propaganda, one possible reason it might have remained hidden for years. It would also set up a "terminus post quem" for the creation of the panels; they would have to have been painted after 1449 (the date of the Battle of Alfarrobeira). That would tend to support the traditional belief that they date from the 1450s (when passions left over from that conflict would still have been fresh), however if the boy depicted in the Panel of the Prince can be identified as the future King John II (b. 1455), his height and appearance would certainly indicate a child older than five years' old, thus a date in the 1460s would be more likely.