The 12th century mosaics in the church of San Clementeare some of the finest in Rome. The mosaics illustrate the story of salvation through the Incarnation of the Son of God and His redeeming sacrifice on the Cross.
The words of Christ from the Gospel of St John, ‘I am the vine, you are the branches’, are recalled in the inscription at the base of the apse: ECCLESIAM CHRISTI VITI SIMILABIMVS ISTI QUAM LEX ARENTEM SED CRVX FACIT ESSE VIRENTEM. (We have likened the Church to this vine; the Law made it wither but the Cross causes it to bloom.) The vine is, in fact, a huge acanthus, which is watered by the blood of Christ, as it flows from the wound in his body. The vine spreads across the apse and we see all manner of people sheltering between its branches. The Church thus becomes the vineyard of the Lord.
According to an ancient legend, the Cross on which Christ was crucified was made from the wood of the Tree of Life in the Garden of Eden. Therefore, Christ through his death redeems the sin of Adam and Eve. The Virgin Mary and St John the Evangelist stand on either side of the Cross, which is festooned with twelve white doves, a reference to the apostles or, perhaps, to the souls of the redeemed. The Cross is surmounted by the hand of God holding a wreath, a symbol of victory, while at the base we see the four rivers of Paradise. The rivers are fed by ‘the river of the water of life, bright as crystal, flowing from the Throne of God and of the Lamb’ (Book of Revelation, 22:1), in other words from the Cross. Two deer drink from the rivers of salvation, recalling the words of Psalm 42: ‘As a hart longs for the flowing streams, so longs my soul for thee, O God.’ At the bottom of the bush a tiny deer sniffs at a serpent, the symbol of sin.
The deer are flanked by two peacocks, symbols of immortality. Beyond the peacocks are a series of scenes depicting everyday life in the middle-ages. A woman feeds her hens; serfs tend their flocks and herds. In line with the foot of the Cross are the four Doctors of the Church, St Ambrose and St Gregory on the right, St Augustine and St Jerome on the left. On the same level as the Doctors are two groups of people, which may represent the family of the artist’s patron.
Lower down, against a blue background, is Christ as the Agnus Dei or Lamb of God. He is joined by twelve lambs (representing the twelve apostles), which emerge from the cities of Bethlehem and Jerusalem. To the left of the gate of Bethlehem, there is an image of a small child. Does this represent the infant Jesus?
At the top of the apsidal arch, we see Christ as Pantokrator (Ruler of all), no longer a martyr on the Cross, but as the judge of all mankind. He holds a book in one hand and raises the other in blessing. He is flanked by symbolic representations of the four evangelists set amongst colourful clouds. At a lower level, and on the left, St Lawrence is learning from St Paul to follow the cross. St Lawrence holds a cross in his left hand and rests his feet on a gridiron, under which a fire is burning. This refers to the manner of his martyrdom, for legend has it that he was roasted alive in 253. Below this group stands the prophet Isaiah holding a scroll inscribed with the words: VIDI DOMINVM SEDENTEM SVP SOLIVM. (I saw the Lord sitting upon a throne.)
On the right, St Peter instructs St Clement: RESPICE PROMISSVM CLEMENS A ME TIBI SVM. (Clement behold Christ promised to you by me.) St Clement is depicted with his feet on a boat, around which fish are swimming. The saint is said to have been martyred by being tied to an anchor and thrown into the Black Sea. He holds an anchor in his left hand, but it has been partly obscured by the 18th century ceiling. Below this group is the prophet Jeremiah, who holds a scroll on which is written: HIC EST DSNR ET NESTIMABIT ALIUS ABSQ ILLO. (This is our Lord and no other can compare with Him.)
At the apex of the vault is the Chi Rho, the monogram of Christ, from which hang the letters alpha and omega, the first and last letters of the Greek alphabet. We recall the words in the Book of Revelation (22:13): ‘I am the alpha and omega, the first and the last, the beginning and the end.’
Framing the whole apse, in gold letters on a blue background, are the words: GLORIA IN EXCELSIS DEO SEDENTI SVP THRONVM ET IN TERRA PAX HOMINIBVS BONAE VOLVNTATIS. (Glory to God on high, seated on the throne, and on earth peace to all men of good will.)