Page from a 42-Line Bible printed by Johann Gutenberg, illustrated by hand
In the fourth century, St. Paulinus of Nola recorded that the portion of the True Cross kept in Jerusalem had a miraculous property; no matter how many pieces were broken from it, its size did not diminish. St. Cyril of Jerusalem compared it to the loaves and fishes that fed multitudes and left over basketfuls. John Calvin famously scoffed that if all the pieces of wood venerated as fragments of the True Cross were collected together, they would make a big shipload. There are studies refuting this claim, but if the old Catholic tradition is to be believed, it might be correct! I doubt that the explanation would satisfy Calvin, a man determined to see fraud; but even he must admit on Biblical evidence that we live in a world in which these sort of things happen.
In another way, relics are inexhaustible even when the Law of Conservation is not miraculously suspended. Catholic tradition maintains that their virtue can imparted through contact. Things that touch the relics of Our Lord’s Passion or the mortal remains of the saints become relics themselves, although of a lower class. When I speak of the virtue of a relic, I do not mean a magical property that works independently of the will of God (for the working of miracles is proper to God alone), but rather the quality that sets it apart from an ordinary piece of wood or bone or cloth. That distinction is real enough to terrify demons.
In the Middle Ages, the faithful believed that this virtue could also be transferred optically; where the relics were inaccessible to touch, pilgrims held up mirrors to reflect them. The mirrors were then carried homeward, and treated as relics of a lower class.
The Cathedral of Aachen is home to four relics of particular distinction: the dress worn by the Blessed Virgin Mary on the night of the Nativity, the Holy Infant’s swaddling cloths, the fabric used to wrap the head of St. John the Baptist and the loincloth worn by Jesus Christ on the cross. Since the fourteenth century, these have been displayed at septennial jubilees, unfurled from the gallery connecting the cathedral’s belfry to its octagonal dome.
In anticipation of the jubilee of 1439, a clever silversmith began to manufacture quantities of pilgrim mirrors, convex ones that could reflect a panorama. He had partners in this enterprise; all were disappointed when the jubilee was postponed due to plague. At a loss for money, the silversmith offered to share with two of his partners another idea, one that he had been developing in secret. They listened, doubled their investments, and set to work on the confidential endeavor. That endeavor involved the making of tiny metal letters that could be arranged into text; a viscous oil-based ink; and a press like that used by vintners and bookbinders, but adapted to the purpose of printing on paper, an art that previously had been done through manual pressure. The silversmith’s name was Johann Gutenberg.
Indirectly, the cult of relics gave Gutenberg his funding. I think that it gave him also the idea for the printing press itself. Consider the mechanism of a printing press: a matrix - which might be a wooden block with a holy picture carved in its surface, or a Biblical text set in forty-two lines of metal type - is inked, and touched to a different object, a piece of paper. Through touch, the matrix makes the paper into something like itself. The process can be repeated with practically no exhaustion of the matrix. Every printer knows that typeset text must run backwards; when printed, images are reversed, just like things reflected in a mirror.
Gutenberg believed that relics can impart their virtue through contact and reflection. In the years when he conceived his printing press, this was at the forefront of his mind, as was the problem of sharing this virtue among great multitudes; we know this as a fact of history. What Gutenberg invented was a technological metaphor for pilgrimage.
In fact, many printed sheets of the fifteenth century were distributed as pilgrim souvenirs; they served the same purpose that pilgrim mirrors did. They served the same purpose served earlier by holy oil flasks and stamps for eulogia bread dough - stamps that were themselves, in fact, tiny manual printing presses. Later scholars gave to the printed books of the fifteenth century the name incunabula; how fitting this is! Incunabula is the Latin word for swaddling cloths, and the Holy Infant’s swaddling cloths were among the relics exhibited at the Aachen jubilee.