Out of the Ashes

It’s not often that two of my interests – computer technology and the Bible – intersect, but they did in a science discovery announced this week. A team of computer specialists at the University of Kentucky were able to read the writing on a 1700-year old Torah scroll that had been turned into charcoal by a fire in 600 CE. How this miracle of science was accomplished and what it uncovered is fascinating.

The Spring of the Young Goat

The story begins on the Western shore of the Dead Sea, a barren desert without tree or shrub except for those around oases such as the one at En-gedi, 35 miles southeast of Jerusalem. En-gedi (the name means “spring of the young goat”) is mentioned a few times in the Bible, most notably as one of the spots where David fled from Saul (1 Sam 24). It was the site of a Jewish community beginning in the 8th century BCE and by the 4th century CE, it was a large Jewish city with at least one synagogue. The city was destroyed by fire in the 7th century during the Arab conquests.

Archaeological excavations in 1970 uncovered the Holy Ark in the ruins of the city’s synagogue. The Holy Ark is a cabinet in a synagogue that holds the scrolls used for synagogue readings. Inside the En-gedi Ark were the charred fragments of its Torah scrolls. The blackened lumps of charcoal fell apart at the touch and there was no way to unwrap them, so the Israel Antiquities Authority (IAA) preserved them on the chance that some future technology would allow them to be read.

Start with a Good Scan

Did the charred scrolls contain any writing at all or were they a total loss? Sefi Porat, one of the excavators who worked on the En-gedi synagogue, asked his colleague, Pnina Shor, head of the Dead Sea Scrolls (DSS) Project at the IAA, if she could scan the En-gedi scrolls as part of the project to create images of all DSS material.

Modern X-ray-based micro-computed tomography (micro-CT) scans of the En-gedi scrolls can reveal there was writing on the layers inside because the ink, containing metals like iron or lead, is denser than the parchment on which it was written and provides a good contrast. The micro-CT scan, designed for high-resolution scanning of biological tissues, can also visualize the layers in the scroll.

But it was impossible to decipher the writing. The Hebrew letters appear on a 3D cylindrical image and cannot be read without conversion to a 2D image. It would be as if you wrote a message on a piece of paper, rolled it up and tried to read it by holding it up to a light. The letters on one layer would be superimposed on the letters on the other layers.

Computer-Assisted Archaeology

This is where the University of Kentucky comes in. Similar charred scrolls were unearthed in the library of Julius Caesar’s father-in-law in Herculaneum, destroyed along with Pompeii in 79 CE. W. Brent Seales, professor and chairman of the computer science department at the University of Kentucky, has spent the last 13 years working on ways to read such damaged scrolls. Dr. Seales and his team developed a technique to “virtually unwrap” the charred scrolls once they had been scanned.

Learning of Dr. Seales’ work, Dr. Shor sent him the micro-CT scan of one of the En-gedi scrolls and asked if he could analyze it.

The program developed by Dr. Seales’ team builds a triangulated surface mesh to identify the layers of material in the scroll. The team identified five complete revolutions of parchment in the scroll. Once the layers had been identified and modeled, the program renders readable textures on the layers by assigning a “brightness” value from the appropriate layer of the CT scan to each point on the segmented surface in the computer model.

Video from The New York Times describing the technique.

Because the layers were rolled-up in the scan, the next step was to flatten the segments. This was done via common 3D-to-2D mapping techniques. The final step was to merge the flattened segments into a composite image. The final image revealed the scroll to be two columns of text that include 35 lines (18 preserved and 17 reconstructed) of Hebrew text from the first two chapters of Leviticus, the third book in the Torah.

A composite image of the completed virtual unwrapping of the En-gedi scroll (source: B. Seales)

The Findings

Radiocarbon results date the scroll to 3rd-4th century CE. This puts the En-gedi scroll a century or two after the period of the Dead Sea Scrolls (3rd century BCE to 2nd century CE) and centuries before medieval biblical fragments found in Cairo dating to the 9th century CE.

The text on the En-gedi scroll is identical to the Masoretic Text (MT). The MT is the text printed in most modern Hebrew Bibles and used as the source for translations into English. This is interesting because the DSS written just one or two centuries earlier reveal some variations in the biblical texts. This discovery pushes back the date for the standardization of the MT to the 3rd-4th century CE.

The work of Dr. Seales and his team was financed by a government grant. The suite of software programs, called Volume Cartography, will be released as open source once the grant ends. Use of the software on the damaged scrolls from the Herculaneum library could re-discover long-lost works of Latin and Greek literature. It is a remarkable accomplishment.

Details of the “virtual unwrapping” technique are detailed in an article published in the 21 Sept 2016 issue of the journal Science Advances.