The cult (system of religious beliefs and rituals) of the saints emerged in the 3rd century and gained momentum from the 4th to the 6th century. The bones of martyrs were believed to provide evidence of God’s power at work in the world, producing miracles and spectacles of the effectiveness of faith. The martyrs had imitated Christ even unto death, and the remains of their holy bodies were thought to be points of contact between earth and heaven. On the model of Christ’s Incarnation, the bones of martyred saints embodied God’s salvific power and thus became the centre of active cults. Relics were installed in basillicas or in special churches called martyria. The tombs of martyrs, on the margins of cities and towns, attracted pilgrims and processions. Legends described the prodigious virtues of martyrs and saints, as well as the dreams or visions that revealed the resting places of still more powerful relics. Each discovery (inventio) promised new and effective signs of divine redemption. Returning from distant places, especially Rome, pilgrims brought relics to their home churches. Thus, during the 8th century, bones and other relics were moved from southern Europe to the north and west.

Of all relic discoveries, the most impressive was that of the True Cross (the cross upon which Jesus was crucified, found in September 335 or in 326, according to other accounts). The discovery of the cross (inventio crucis) was one of the more popular legends of the Middle Ages. The basic elements of the tradition had been established by the late 4th century and were associated with a pilgrimage that St. Helena, mother of the emperor Constantine, made to Jerusalem in the 320s. According to the legend, Helena, prompted by a dream, located the place where the cross lay buried and had the wood unearthed. Helena, the tale continues, realized that what she had found was the True Cross when a sick woman she had lie on it was healed. The power of the cross, the history of the wood, and the story of its discovery became legendary.

Through the symbolism of the cross, early Christian imagery perpetuated, and at the same time transformed, the myths of the World Tree. The sacred drama of Christ’s birth, death, and Resurrection participates in the rejuvenating rhythms of the fecund cosmos. Early Christians identified the cross of Christ as the World Tree, which stood at the centre of cosmic space and stretched from earth to heaven. The cross was fashioned of wood from the tree of knowledge of good and evil, which grew in the Garden of Eden. Below the tree lies Adam’s buried skull, baptized in Christ’s blood. The bloodied cross-tree gives forth the oil, wheat, grapes, and herbs used to prepare the materials administered in the sacraments that revitalize a fallen world. The Italian Renaissance painter Piero della Francesca later depicted the myth of the True Cross in his frescoes in Arezzo, Italy. They portray the death of Adam, fallen at the foot of the tree that provides wood for the crucifix on which Jesus is slain. The wood of the cross, however, becomes the instrument of salvation and the holiest matter in Christendom, and the cross itself became the focus of tales of fantastic historical episodes.

Helena was responsible for another great discovery when she found Christ’s tomb, the Holy Sepulchre in Jerusalem, which also became a highlight of Christian legend. Like the body of the Saviour, the tomb is a “holy of holies.” Its discovery was tantamount to the Resurrection, for its reemergence into the light of day was seen as a restoration of life where before only darkness reigned. The cross and the tomb were woven together in legend. The desire to regain possession of the True Cross and the Holy Sepulchre was the source of inspiration for the Christian knights of the Crusades.