The arrangement of the various scenes over the left and right doors reveals a carefully thought-out scheme. The scenes on the left door, under the figure of Christ, visualize the temporal aspect of the pope’s authority. They show the emperors John VIII Palaeologus and Sigismund both kneeling for Pope Eugenius, and between them Saint Paul, whose traditional attribute of a sword is prominently put on view, evoking associations with “the sword of the Spirit” (Ephesians 6:17). On the right door, scenes showing the unification of the church under Pope Eugenius IV as its supreme leader illustrate the spiritual power of the papacy. The central panel, with Saint Peter handing the keys to Eugenius, underscores the pope’s unlimited authority. Together, the doors bear out the papal claims of plenitude of power in both temporal and spiritual matters. These are the claims made by any pope, but within the difficult circumstances of the 1430s and 1440s they were especially relevant for Eugenius IV. The universal claims and entitlements of the papacy, which are the concerns of any pope in any time, are demonstrated via one specific pope, Eugenius IV, giving the events of his life a timeless dimension. This careful balancing of generality and specificity set the example for papal propaganda in the two centuries to come.
The fresco paintings on the walls of the Sistine Chapel offer another example of papal propaganda (fig. 4).10 They were commissioned by Sixtus IV, who was, more than thirty years after Eugenius, still battling with the general council. The conflict had flared up because of Sixtus’s ruthless aggrandizement of the papacy and of his own family. At the same time, the French King Louis XI, with whom he had strained relations, tried to outmaneuver him by appealing to a general council. The general council thus not only constituted a threat to the papal authority from within the church, but was prone to be (mis)used by secular rulers as a political instrument to put pressure on the pope. Sixtus’s response, as we have seen, was to annul the decrees of the Council of Constance and renew the Execrabilis bull, which forbade appeals to the general council. From 1481 to 1483 he had his claims to full papal authority visualized and legitimized on the walls of the Sistine Chapel. This was part of a project that Sixtus had started in 1477, which involved the construction and decoration of the chapel for official celebrations by the pope and his court. The decoration consisted of paintings by a team of prominent artists, headed by Pietro Perugino and including Sandro Botticelli, Domenico Ghirlandaio, Cosimo Rosselli, and Luca Signorelli. The paintings depicted a parallel series of scenes from the lives of Moses and Christ. The two series started on the altar wall with The Finding of Moses and The Birth of Christ (both destroyed in the 1530s to make room for Michelangelo’s Last Judgment), continued over the two long walls, and concluded on the entrance wall with The Fight over the Dead Body of Moses and The Resurrection and Ascension of Christ (also lost in the sixteenth century, but soon replaced by new ones on the same subject; fig. 5). The frescoes that still remain on the south and north walls show closely corresponding episodes from the lives of Moses and Christ. The Trials of Moses (fig. 6), for instance, is matched by The Temptations of Christ (fig. 7), which is situated directly opposite it. The Latin captions help make the correspondence more explicit, as both use the word temptatio.11 Thus, the scenes on the south wall show Moses as a representative of the Old Testament, whose deeds find their fulfillment in Christ and the New Testament. Another example is Moses Receiving the Tablets with the Ten Commandments (fig. 8), which is matched by Christ’s Sermon on the Mount (fig. 9). The captions explain that both episodes deal with promulgatio legis: promulgation of the law, respectively, of the Old and the New Testament.12 Moses is thus represented as a sort of precursor, who instituted the rules of God that would be fulfilled by those of Christ.
One pair of corresponding paintings illustrates this point in particular. A fresco on the south wall, painted by Botticelli, shows several episodes of a revolt against the leadership of Moses and the supreme priesthood of his brother Aaron during Israel’s forty-year passage through the desert (fig. 10). God’s intervention, however, made the earth swallow the leaders of the revolt and restored Moses’s and Aaron’s authority.13 The caption explains the theme as “the threat [Conturbatio] to Moses, the bearer of the tablets of the Law.”14 An inscription within the painting further explains this. On a building in the background that closely resembles the Roman Arch of Constantine (at first sight a curious addition to a desert scene) is written a quote from the New Testament: “Neither doth any man take the honor to himself, but he that is called by God, as Aaron was.”15 This makes it clear that the leadership of God’s people and the supreme priesthood are divinely instituted and not to be challenged by anybody. The reference to the general council disputing the pope’s full authority is obvious.
The corresponding fresco on the opposite wall, by Pietro Perugino, makes this message even more apparent (fig. 11). According to the caption, it illustrates “the threat [Conturbatio] to Jesus Christ, the lawgiver,”16 but this is actually only to be seen in the right background. According to the Gospel of John,17 Christ was twice on the point of being stoned when he professed to be God’s son, but both times he managed to walk away unharmed. The foreground of the painting prominently displays an episode that is literally the key passage of the papal institution: Christ handing the keys of heaven and earth to Saint Peter, according to the text in Matthew.18 Again it is hard to miss the reference to the pope’s plenitude of power and, by implication, to the unsubstantiated claims of the general council.
Just as in the bronze doors of Saint Peter’s, a balance is struck in the chapel frescoes between generality and specificity. They all represent episodes from the Bible, whose importance for any believer in any time is beyond doubt, and imply that if God helped (the leaders of) the faithful in the past, he will also sustain them in the future. The urgency of this message is underlined by the inclusion of contemporary details, such as portraits of members of the papal court and present-day buildings in Rome. Thus, they link the disastrous attempts to challenge the authority of Moses and Christ to the endeavor to curb the power of the pope in the 1470s and ’80s, making it clear that any attempt to dispute papal authority is bound to fail. Just like Christ’s biblical parables, the paintings appeal to those who have ears to hear.19 The direct and continuing link between Moses and Christ and the present-day pope (whoever may hold that position) is further illustrated by the series of popes painted between the windows, above the biblical scenes (fig. 12). They show (fantasized) portraits of the supreme pontiffs from Saint Peter until the year 313, when Constantine the Great officially recognized Christianity. The implication is that this series is continued by the living pope. Thus, a direct connection is visualized from the current pope, via his predecessors, to Christ and Moses, the lawgivers of the New and Old Testaments,