Detectives read captivating old letters without opening them

On July 31 In 1697, Jacques Sennacques sent a letter to his cousin – Pierre Le Pers, a French merchant living in The Hague – asking him, for Pete’s love (which is paraphrased), to send him a death certificate for his relative, Daniel Le Pers. In a seventeenth-century version of the dreaded “according to my previous e-mail,” Sennacques wrote, “I am writing to you a second time to remind you of the pain I have taken in your name.” Basically, you owe me a favor and I came to collect.

Sennacques put down his pen and folded the letter, turning it into his own envelope. Today, historians call this technique “letter blocking.” In Sennacques’ time, people had come up with a galaxy with different ways of folding their letters – some so characteristic, in fact, that they acted as a kind of signature for the sender. They were not doing this because they wanted to save money on envelopes, attention, but because they wanted privacy. By folding the paper and pushing the corners, they could arrange it in such a way that, in order to open the correspondence, the reader had to tear it in certain places. If the intended recipient opened the letter and found it already torn, he would know that a suspicion had entered. Whole pieces of paper could tear, so if they opened the letter and didn’t feel or hear any tears, yet a piece was still falling, they would know they weren’t the first person to read the contents.

The modern early version of one of those seals has voided the warranty of a device if you break it. Unlike the self-destruction messages in Mission impossible, you might read another broken letter, and if you were familiar with the technique of the person who sent it to you, you might even know tricks to avoid breaking it in the first place. However, blocking the letters set traps for the spies.

Unfortunately for all parties involved, Sennacques’ second letter never reached his trading cousin. Instead, it ended up in a trunk, known as the Brienne Collection, which contained 2,600 letters sent between 1689 and 1706 from all over Europe to The Hague. Sennacques’s letter is one of hundreds that remain unopened, folded tightly in itself.

Then how do we know that the man lost his temper with his cousin? Writing in the diary today Communications about nature, The researchers describe how they used an advanced 3D imaging technique – originally designed to map the mineral content of teeth – to scan four old letters from the Brienne Collection to carry them out virtually without breaking. “The letters in his trunk are so sharp that they tell such important stories about family, loss, love and religion,” says King’s College literary historian Daniel Starza Smith, co-author of the newspaper. “But also what letterlocking does is give us a language to talk about types of security technologies and the secrecy of human communication and discretion and confidentiality.”