The marble pavement of the cathedral is an extraordinary work, one of a kind: no other large church in Christendom can boast an artistic creation comparable to this in terms of its complexity of composition and quality of execution. In accordance with the medieval view that every large church was a place for entering into knowledge, even the part of the cathedral destined to be walked on was utilized to give shape to a ‘journey through images’ that, starting from the times before Christ was born, leads the faithful to the Revelation.
Despite the fact that it was begun in the second half of the fourteenth century and finished almost two centuries later, the pavement manifests a unified, organic conception. Some of the greatest artists born or working in Siena took part in its realization: Domenico di Niccolò dei Cori, Domenico di Bartolo, Matteo di Giovanni, Neroccio di Bartolomeo, Pinturicchio, Domenico Beccafumi, and others. They furnished the preparatory drawings for the fifty-six inlays that make it up, translated by master stonecutters using the techniques of marble inlay and graffito. The pavement has been subjected over the centuries to numerous restorations, and parts have been remade, operations necessary because of the wear and tear to which it is constantly subjected by its very nature. Precisely in order to preserve it from wear, the decision has been made to keep it covered for a large part of the year and to open it for viewing just for a couple of months, from late August to October.
The first part of the path through the illustrations, which embraces the central nave and two side aisles, begins with the panel showing Hermes Trismegistus, the great philosopher who gave the Egyptians the book of knowledge. Knowledge lies at the base of Revelation and gives rise to the Christological prophecies of the Sibyls, shown in the inlays in the side aisles. According to the Fathers of the Church, these prophetesses foretold the fundamental dogmas of the Christian religion: the Annunciation, Nativity, Passion, Resurrection, and Last Judgment. Christ is therefore the fulfillment of truth which the pagans had intuited.
The path along the nave continues with some inlays whose purpose is to show that the climb towards Knowledge is made by throwing aside earthly fortunes. This is the meaning, for example, of the fourth panel, designed by Pinturicchio, in which some sages pursue an uphill path rife with danger in order to reach the summit of the hill where, in the serenity of a high plateau covered with flowering shrubs, sits a female figure who symbolizes Knowledge.
From the classical and pagan antiquity of the nave, we come in the transept to pictures of Bible stories; the experience of the Hebrew people is illustrated as it is narrated in the Old Testament, the first revelation of God.
Progressing towards the altar, we come to the evocation of the figures who foreshadowed Christ. The large central hexagon, situated directly under the dome, holds Stories of Elijah, the prophet of the living God, who rose to heaven in a fiery chariot, foreshadowing the ascension of Christ; this episode also brings to mind the Assumption of the Virgin Mary shown in the center of the stained-glass window in the apse. The next panel shows Moses, the prophet and leader of the Hebrew people, receiving the Tablets of the Law from God: Jesus is the new Moses who proclaims the law of the new covenant and leads God’s people to true, definitive freedom. Still approaching the altar, we come to David, King of Israel, priest and psalmist, the Messianic figure par excellence, so much so that Christ was also called the ‘son of David.’
The broad thematic design of the floor concludes with the scene of the Sacrifice of Isaac, placed not coincidentally in front of the altar, the place where Christ’s sacrifice on the cross is continually re-enacted. This inlay, an outstanding masterpiece by Domenico Beccafumi, presents the episode in the Bible when God, to test Abraham’s obedience, commands him to burn his son Isaac on the altar; while Abraham is about to perform the sacrifice, an angel of the Lord descends to stop him.
The journey towards salvation that takes place in the time of human history thus leads to Christ; constantly evoked but never represented in the pavement, He is present on the altar, the fulcrum onto which the entire path converges.