Level 1 — Absolute Beginner

Long ago, people wrote letters on clay. This was almost 4,000 years ago. Some letters went inside a clay cover, like an envelope today.

The clay cover kept the letter private. It also showed that nobody opened the letter before it arrived. Many of these old clay covers are still whole today. But nobody could read the letters inside without breaking the covers.

Now scientists have a new machine. It is called ENCI. It uses X-rays to look inside the clay cover. It can read the writing without breaking the clay.

Scientists Cecile Michel and Christian Schroer made this machine with a team in Germany. They tested it on a real clay letter from a merchant named Shalim Assur. This new tool helps us read old letters and keep them safe too.

clay

A soft, wet earth that becomes hard when it dries.

envelope

A cover that holds a letter inside.

scientist

A person who studies and learns about the world.

machine

A tool that helps people do work.

ancient

Very, very old.

merchant

A person who buys and sells things.

letter

A written message sent to another person.

seal

A special mark pressed into clay to show who sent something.

Level 2 — Elementary

Nearly 4,000 years ago, in the nineteenth and eighteenth centuries BCE, Assyrian merchants lived far from their homes. They lived in a city called Kanesh, in what is now central Turkey. Their families and business partners wrote to them from the city of Assur, in northern Iraq, about 1,000 kilometers away.

Many letters were written on small clay tablets. To keep the letters private and to prove they had not been opened, people wrapped the tablets in an outer layer of clay, like an envelope. Several hundred of these sealed clay envelopes have survived until today.

Until recently, the only way to read a letter inside an envelope was to break it open. Breaking it destroyed the seal marks stamped on the outside, and those seals held useful information about ancient officials and trade.

Now a team of scientists has built a new tool called ENCI, short for Extracting Non destructively Cuneiform Inscriptions. Led by Assyriologist Cecile Michel and physicist Christian Schroer, with help from the University of Hamburg and the DESY research center, the team can scan the sealed envelopes with X-rays. This lets them read the hidden letters and study the clay without ever opening the envelope.

Assyriologist

A scientist who studies the ancient Assyrian civilization and its writing.

tamper

To change or damage something without permission.

seal

A stamped mark on clay that proves who sent an item and that it was not opened.

excavate

To dig up something buried in the ground, such as ancient objects.

tablet

A flat piece of clay or stone used for writing in ancient times.

transportable

Able to be carried or moved easily from place to place.

cuneiform

An ancient system of writing made with wedge shaped marks pressed into clay.

physicist

A scientist who studies matter, energy, and how things move.

Level 3 — Intermediate

Nearly four thousand years ago, during the nineteenth and eighteenth centuries BCE, Assyrian merchants who had settled roughly a thousand kilometers from home, in the city of Kanesh in central Anatolia, kept in close contact with relatives and business associates back in Assur, in what is now northern Iraq, through letters written on small clay tablets.

Because these messages often concerned private family matters or valuable trade deals, many tablets were enclosed within an outer shell of clay, functioning much like a sealed envelope, and stamped with seals that both protected privacy and offered proof against tampering. Several hundred of these sealed envelopes have survived intact into the present day.

Until now, the only way to access the letter hidden inside was to physically break the envelope open, an act that permanently destroyed the fine seal impressions pressed into the clay, robbing researchers of evidence about ancient administrative practices and the individuals who used those seals.

A team led by Assyriologist Cecile Michel and X-ray physicist Christian G. Schroer, working with specialists at the University of Hamburg and the German research center DESY, has now developed a transportable, high definition computed tomography scanner nicknamed ENCI. Because the device can be brought directly to museums and archives, fragile tablets no longer need to travel to a laboratory, and researchers can examine both the hidden inscriptions and the composition of the clay itself without ever opening the envelope. One such envelope, catalogued as Kt 94/k 1150 and excavated from the house of a merchant named Shalim Assur in the lower town of Kanesh, dates to the first half of the nineteenth century BCE and shows how much information can now be recovered without loss.

computed tomography

An imaging technique that uses X-rays taken from many angles to build a detailed picture of an object's interior.

nondestructive

Describing a method that examines or tests an object without damaging or altering it.

inscription

Writing carved, stamped, or pressed into a hard surface such as stone or clay.

impression

A mark left by pressing an object, such as a seal, into a soft material.

administrative

Relating to the organization, management, or record keeping of an activity or institution.

archive

A place where historical documents or records are collected and kept.

intact

Complete and undamaged, not broken or altered in any way.

associate

A person who is connected to another through business or shared activity.

Level 4 — Advanced

Some four millennia ago, in the nineteenth and eighteenth centuries BCE, a community of Assyrian merchants residing roughly a thousand kilometers from their ancestral city of Assur, in what is now northern Iraq, conducted much of their private and commercial correspondence from the trading outpost of Kanesh, in central Anatolia, present day Turkey. Letters from family members and business partners arrived on small inscribed clay tablets, many of which were subsequently enclosed within an outer casing of clay that functioned as a sealed envelope, stamped with impressions intended both to safeguard confidentiality and to guarantee that the contents had not been altered in transit.

Several hundred of these sealed envelopes have survived to the present day in essentially intact condition, a remarkable archaeological legacy. Until recently, however, that very state of preservation posed a dilemma: the only means of retrieving the letter concealed within was to physically fracture the envelope, an irreversible act that obliterated the delicate seal impressions on its exterior and, with them, a substantial body of evidence bearing on ancient administrative practice and the individuals whose seals authenticated these documents.

That dilemma has now been resolved through the development of ENCI, an acronym for Extracting Non destructively Cuneiform Inscriptions, a transportable, high definition computed tomography scanner devised by a team led by the Assyriologist Cecile Michel and the X-ray physicist Christian G. Schroer, in collaboration with specialists at the University of Hamburg and the German research center DESY. Because the instrument can be deployed on site within museums and archives, fragile artifacts need never be transported to a distant laboratory, a logistical constraint that has long limited such research.

Using ENCI, the researchers can now visualize the cuneiform script inscribed on a tablet sealed within its envelope and investigate the composition and manufacture of the surrounding clay, all without compromising the object's structural integrity. The team's published findings, which appeared in the journal npj Heritage Science, are illustrated by the case of Kt 94/k 1150, an envelope and its enclosed tablet excavated from the residence of a merchant named Shalim Assur in the lower town of Kanesh and dated to the first half of the nineteenth century BCE, a striking demonstration of how much can now be recovered from an object that a generation ago would have yielded its secrets only through destruction.

correspondence

Communication carried out through letters or written messages.

confidentiality

The state of keeping information private and protected from unauthorized access.

irreversible

Impossible to undo or reverse once it has occurred.

authenticate

To prove that something is genuine or has not been altered.

deploy