It was a letter that was saved 300 years ago. It had a special seal that had to be broken to be read. The seal was the letter itself, turned into its own envelope: an ancient technique. How did you do it? Use of an X-ray scanner. Used in dental research. But thanks to this, the letter was revealed, which was read without being opened.
They did not break the seal or damage it in any way. The manuscript was “virtualized” and, for security reasons, folded several times in its own envelope. The feat was reported in the journal Nature Communications. It opens the door for other ancient texts to be read without the risk of spoiling them forever.
The letter comes from an unopened lot in the Brienne collection. It is a mailbox that is kept in the Museum of Communication in The Hague. It contains … 2,600 undelivered letters that were sent to The Hague from all over Europe between 1680 and 1706. The senders of these letters had them closed with “letter blocking”. They would fold a flat sheet of paper in their own envelope. It was a common practice for secure communication before modern envelopes came into use. The missing link between old security technologies for physical communication and modern digital cryptography.
Previously, these parcels of letters could only be studied and read by cutting. Now they were using a highly sensitive X-ray microtomography scanner. The scanner was originally designed to map the mineral content of teeth with unprecedented sensitivity. “It was possible to dissolve certain types of ink on paper and parchment. It is amazing to believe that a tooth viewing scanner has got us this far. ‘So says Graham Davis, co-author of the study. “You can see the tiny traces of metal in the ink that these letters were written with.”
The rest of the team was able to convert the scanned images into letters that could be opened virtually. The researchers then applied computational algorithms to the scanned images. And they managed to separate the different layers of the folded sheet and “virtually unfold” them.
What is the content of this letter? It is dated July 31, 1697. It contains a request for a physical copy of a Daniel Le Pers’s death certificate. The investigation team explains, “Sometimes the past defies control. We could have just opened these letters. But we take the time to examine them for their hidden, secret and inaccessible properties. We learned that cards can be much more revealing if left unopened. We use the virtual display to read an intimate story that has never seen the light of day. It hasn’t even reached its addressee yet, it’s really extraordinary. The letter that was read unopened is certainly the first of its kind.