A Sign of Contradiction: The Apse Mosaic of San Clemente


November 22, 2012

Among the most beautiful and fascinating of Rome’s churches is the twelfth-century Basilica of San Clemente, dedicated to Pope St. Clement, who, according to early lists and reckonings of Rome’s first bishops, stands either first or third in the line of St. Peter’s successors. The apse mosaic, which sits above the high altar of San Clemente as the basilica’s crowning jewel, presents itself as a fitting subject for reflection as we celebrate the feast of Pope St. Clement on this Friday, November 23, 2012. The mosaic’s central motif has much to teach us about papal conceptions of power and authority that are as relevant today as they were in the twelfth century.

The focal point of this stunning mosaic is Christ on the Cross, depicted as the Tree of Life, from which flow the four rivers of paradise restored. Sprouting from an acanthus plant at the base of the Tree of Life are numerous vines, which nourish a breathtaking variety of images: birds, hinds, baskets filled with fruit, putti (pagan cupids), a shepherd with his sheep, a peasant woman feeding chickens, and the Doctors of the Church, just to mention a few. Taken together, these images symbolize the fecundity of nature and culture (secular and sacred, pagan and Christian), which find their origin in the life-generating power of the Cross. The vine motif is echoed in the mosaic floor that extends up the central aisle of the nave, as if to extend the offer of paradise to all who enter the church.

The half-dome, whose focal point is the Tree of Life, is set within a triumphal arch that tells the story of salvation history culminating in Christ, the eternal Logos, represented in the medallion set at the center point of the arch. On the right side of the arch, moving from base to top, we find the city of Jerusalem, the prophet Jeremiah, and Saints Peter and Clement. On the left we find Bethlehem at the base, the prophet Isaiah, then Saints Paul and Lawrence. Thus, just as the half dome depicts Christ crucified as the life-giving source of all things in nature and culture, the triumphal arch depicts Christ glorified, the eternal Logos, in whom nature and culture find their fulfillment and end.

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Although those responsible for the mosaic’s design are unknown, it is clear that they wanted to convey a particular understanding of Rome’s history. The basilica itself is a living embodiment of this history, offering visitors today a journey deep into Rome’s past. Excavations begun in the nineteenth century beneath the present-day basilica discovered the remains of a late-fourth or early fifth-century basilica, also dedicated to Saint Clement. Below this early basilica is yet another layer of structures, some of which date back to the first century. Among the buildings found at this lowest level are a warehouse and a Mithraic temple, probably dating to the late second or third century.

While the builders of the twelfth-century basilica were unaware of the first-century structures at the lowest level, they were certainly aware of the 4th/5th-century basilica, which they filled in with earth and used as a foundation upon which to rebuild the twelfth-century basilica, which still stands today. It is not altogether clear why the decision was made to build anew, rather than to renovate, but it appears that some combination of practical and cultural reasons were in play. On the practical side of things, the late-antique basilica had grown old. It had undergone significant renovations under Pope Hadrian I (772-795), and again under Pope Leo IV (847-855). Sometime between 1084 and 1099, Cardinal Rainerius, the titular cardinal of San Clemente—later Pope Paschal II (1099-1118)—began another series of renovations aimed at shoring up the basilica’s interior walls. There is reason to believe that the structure’s stability may have been compromised. Due to the natural silting process evident in so many parts of Rome, the late-antique basilica was already five meters below street level by 1100. It is possible that the structure may have been further weakened by an earthquake.

On the cultural side, Rome was the epicenter of the Investiture Controversy, an epic struggle between the papacy and the German emperors to define the proper relation between secular and spiritual authority. This tumultuous struggle, which caused much distress and turmoil in Rome from the 1070s through the 1120s, found its ultimate source in a dynamic tension that goes to the very roots of medieval society. As Christopher Dawson noted, the historical circumstances in which the barbarian successor states replaced the Late Roman Empire in the early Middle Ages gave birth to a “dualism between cultural leadership and political power.” This tension gave rise to two equal and opposite dangers, a Scylla and Charybdis through which it was medieval society’s task to steer. On the one hand, there was the danger of an overweening State forcing or coaxing the Church to become an institutional voice for a civil religion, not unlike that of the state religion of Rome’s Augustan age and, arguably, not unlike contemporary versions of civil religion which so readily acquiesce to domestic and foreign raisons d’état. On the other side was the danger of a “religious absolutism” that fails to respect the legitimacy and integrity of this-worldly flourishing, reducing all to a heavy-handed theocracy. The challenge of negotiating this tension produced a flourishing culture in the Middle Ages and abiding fruit for its heirs. Of course, the wonderful capacity, so evident in Catholic thought and culture, to hold things in a dynamic and fruitful tension finds its ultimate roots in the Incarnation; but the medieval dualism to which Dawson refers created conditions favorable for working out the implications of the Incarnation in so many spheres of human activity.

And so, we turn back to the apse mosaic. Beneath the triumphal arch, traditionally a symbol of imperial power, there is the sign of contradiction: Christ crucified. Power and self-emptying are held in dynamic tension, the latter disciplining the former. But there is more. The imperial party, which included many of Rome’s nobles who wanted to free Rome from papal control, argued that the German emperor was the legitimate heir to imperial Rome. Just as Roman law, whose source and guarantor was the emperor, brought peace and order to the world in the days of Imperial Rome’s glory, so too, a revival of Roman law, guaranteed by the German emperors, was the sine qua non for the restoration of peace and justice to the troubled world of the twelfth century. All well and good, but the apse mosaic reminds us that there is a danger lurking in such political visions. Across the bottom of the mosaic runs the following inscription. Ecclesiam Cristi viti similabimus isti quam lex arentem, set crus facit esse virentem, “We have compared the Church of Christ to this vine; the Law made it wither but the Cross made it bloom.” Drawing upon St. Paul’s analysis of Old Testament Law, the designer of the apse mosaic saw a danger to which any reliance on law is prone. It is the same danger to which T.S. Eliot draws attention in his poem, Choruses from the Rock. Critiquing the modern propensity toward bureaucratic solutions, he writes,

They constantly try to escape
From the darkness outside and within
By dreaming of systems so perfect that no one will need to be good.

Certainly there is no denying the necessity of law and the benefits derived from it, but an unmeasured reliance on law—one removed from the refining effect of the above-mentioned dualism—reduces the human good to an exoskeleton, engineered from without by a panel of experts. Under such conditions the human soul withers, as does the culture that is its blossom. Well-crafted laws are important pedagogical tools, but a human being requires nourishment from within, and for this, one must be connected to the vine—to the sacramental life of the Church. Such was the message of San Clemente’s apse mosaic, and a prophetic one at that.


  • David Foote

    David Foote is Associate Professor of History at the University of St. Thomas in St. Paul, Minnesota. His teaching and research focuses on medieval church and society, especially the role of the church in the development of the Italian city-states.

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