Measuring Belief: The Shroud of Turin, Analog and Digital

Balliani SindoneCamillo Balliani, Ragionamenti della Sacra Sindone (Turin: 1610), unpaginated front matter.
Image: Google Books

With the second-ever televised ostension planned for Holy Saturday (this year 30 March), and the introduction of a new “Shroud app,” the custodians of the Shroud of Turin once again are using contemporary technology to promote devotion to the controversial relic. They thus continue a centuries-old tradition already well established when the Shroud first arrived in Turin in 1578.

Relics witness to a holy event or person in the past, serve as aids to devotion, and are themselves occasionally objects of devotion. An implicit proof of authenticity is inherent in a relic’s very existence: the relic vividly evokes historic events with its materiality in the here and now, confirming that the events actually took place even once eyewitnesses are gone. The relic itself provides a kind of “proof” for believers that simultaneously challenges the skeptic to question and critically examine. The Shroud, ostensibly bearing traces of Christ’s own blood, is a particularly important relic that demands the devotion due to God himself.*

SINDONEThe Shroud of Turin
Image: Wikimedia Commons / public domain

The testing and examination of the Shroud has increased in recent decades, with results dividing believers and non-believers into ever more entrenched camps. But the use of quantification to describe the relic is not new. In 1610, for instance, Camillo Balliani published his Ragionamenti della Sacra Sindone, a devotional book on the Shroud, which featured an image of the textile entitled “Ritratto della Sacra Sindone,” the “Portrait of the Holy Shroud” (above). Two points labeled “A” and “B” flank the base of the image, providing a fixed length to assist the faithful in calculating the dimensions of the cloth. The caption below explains:

“The measure of the Holy Shroud, and of the Image of Our Savior which remains on it.
From A to B, that is from one point to another, thirty-six times [this measure] is the length of the Shroud.
From A to B, twelve times [this measure] is the height, or rather width of it.
From A to B, sixteen times [this measure] is the length of the Image of the Lord.
From A to B, four times [this measure] is the width of the shoulders.”

The A to B measurement given directly on the page cleverly sidestepped the confusion of regional unit measures then prevalent in Europe. It also required no advanced numeracy among its readers, since the necessary calculations or mental constructions could be performed geometrically with simple counting of iterations. (What the caption does not calculate is the gigantic size of the three angels displaying the Shroud, each of them easily twice the size of the life-sized image of Christ.)

Passion relicsBalliani’s Shroud image thus belongs to the “metric relics” dating back to the medieval period, a group of artifacts – particularly those of the Passion – for which devotional function was enhanced by indication of the relics’ actual size.** Such metric relics took their first technological leap (from manuscript to print) already during the sixteenth century, just decades before Balliani.

Anonymous German, Twelve Holy Relics,
with measurement scale, drawing, 17th century

Image: © The Trustees of the British Museum

Devotion to the Shroud and examination of the textile again entered a new technological era in 1898, when the first photographs of the relic were taken by Secondo Pia.  As he was developing the photographic plates, Pia realized the Shroud itself was a negative of the body’s image (Scott, p. 302) The negative of this negative produced a positive image, an even more convincing simulacrum of the dead Christ, and one that was readily disseminated through mass print reproduction. The faithful were fascinated by this discovery, but at the same time it ushered in a technological arms race between believers and skeptics which continues to this day.

Shroud negative Gallica

Shroud of Turin, negative detail of face, 1932
Image: / Bibliothèque nationale de France / Planet News

Despite their transmission via new media technologies, photography and measurement also dominate the most recent devotional aids. The new Shroud app will reportedly allow users to inspect an ultra-high resolution image of the relic on mobile devices, a function already available online on several Shroud-related websites. The Shroud Scope at is perhaps the most elaborate of these tools, since it permits users to measure between any two click points, adjusting for the zoom scale, and it also documents blood stains, burn marks, poker holes, and the sites from which samples have been taken for carbon-14 dating. This clickable measurement function thus continues the manuscript and print tradition of metric relics in a renewed technological leap, this time to digital media.

As a devotional exercise, the action of tracing these images of the textile with the cursor reassures believers that the relic withstands the scrutiny of contemporary technology, while maintaining the substantial historic traditions of earlier ostensions and devotions, albeit in transposed format. The nearly haptic process of virtually inspecting the digitized Shroud millimeter by millimeter recalls the physical manipulations of earlier metric relics, or the spatial and temporal dimensions of other devotions focusing on the Passion, such as Stations of the Cross or Sacri Monti chapels, which unfold as the pilgrim moves through a prescribed sequence of experiences.


Wolf Traut after Albrecht Dürer, [The Hand of God, or an invitation to prayer], woodcut, 1511
The new media of the Renaissance: here, the hand of God appears as a sort of heavenly cursor pointing out scenes from the Passion
Image: © The Trustees of the British Museum

What both sides in the Shroud controversy sometimes seem to forget in the race for technological confirmation and dissemination of their positions is that the message of Easter need not be linked to the authenticity (or not) of this particular textile. Belief cannot be measured in millimeters and pixels, nor dated with carbon-14.

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*On the particular properties of the Shroud as a relic, see John Beldon Scott, Architecture for the Shroud (Chicago: University of Chicago Press, 2003): 115-117, and passim.

**Among the rich literature on metric relics, their use for devotion and as amulets, two examples available online may be cited here: Adolf D. Jacobi, “Heilige Längenmasse: Eine Untersuchung zur Geschichte der Amulette,” Schweizerisches Archiv für Volkskunde 29 (1929): 1-17, 181-216; and Kathryn M. Rudy, “Kissing Images, Unfurling Rolls, Measuring Wounds, Sewing Badges and Carrying Talismans: Considering Some Harley Manuscripts through the Physical Rituals they Reveal,” Electronic British Library Journal (2011): article 5.