Aug 5, 2026 · 3 min · 3 segments
Our season is over but Producer Emily will be giving you quick bites of history until we return for next season. Today's History Bite: What is Letterlocking? Some questions for our AI guests: How do…
In the 1200 CE throughout Europe, there appeared a new fad sweeping the world of letter writing, and that was called letter locking.
Sending messages in the European medieval era was really hard.
Many places didn't have anything like a postal service, so you just had to ask someone to deliver a letter for you.
Since they hadn't started using envelopes, the best way to seal a letter so no one could read it was through letter locking.
There are many ways to practice letter locking.
For instance, Mary, Queen of Scots would lock her letters with a spiral lock, where a strip from the side of the paper was put through the hole in the letter itself.
Then she would wrap the paper strip around the side and loop it back through the hole until it formed a tight binding.
No glue or wax was needed.
This was a great way to lock your letter from prying eyes.
It would also let you know if someone had read your letter.
With the spiral lock method, you'd have to break the thin strip of paper woven through the letter to read anything.
Some of the methods used for letter locking looked like complicated rolls or would have strips of paper to lock the letters closed, and some looked more like origami, relying on the complicated folding of the paper to keep the message a secret.
Sometimes when people, called archivists, who take care of old documents, came across an old letter and see that it's ripped and crumpled, they didn't always realize that could be evidence of letter locking.
A lot of these techniques have been lost.
However, in 1926 CE, a museum acquired a trunk of letters owned by two former Dutch postmasters from the 1600s that helped advance our understanding of letter locking.
Back then, you had to pay to retrieve your letter from the post, so if you refused to pay or didn't come at all, the post office would keep your letter.
The trunk held 2,600 letters.
Nearly 600 of them had remained unopened since the 1600s.
These letters were such a rich source of not just everyday messages of people at the time, but also the ways in which letter locking was used by everyday people.
Scientists have now found a way that we can digitally unfold these letters so that we can read them without damaging the letter lock.
In the 1200 CE throughout Europe, there appeared a new fad sweeping the world of letter writing, and that was called letter locking.
Sending messages in the European medieval era was really hard.
Many places didn't have anything like a postal service, so you just had to ask someone to deliver a letter for you.
Since they hadn't started using envelopes, the best way to seal a letter so no one could read it was through letter locking.
There are many ways to practice letter locking.
For instance, Mary, Queen of Scots would lock her letters with a spiral lock, where a strip from the side of the paper was put through the hole in the letter itself.
Then she would wrap the paper strip around the side and loop it back through the hole until it formed a tight binding.
No glue or wax was needed.
This was a great way to lock your letter from prying eyes.
It would also let you know if someone had read your letter.
With the spiral lock method, you'd have to break the thin strip of paper woven through the letter to read anything.
Some of the methods used for letter locking looked like complicated rolls or would have strips of paper to lock the letters closed, and some looked more like origami, relying on the complicated folding of the paper to keep the message a secret.
Sometimes when people, called archivists, who take care of old documents, came across an old letter and see that it's ripped and crumpled, they didn't always realize that could be evidence of letter locking.
A lot of these techniques have been lost.
However, in 1926 CE, a museum acquired a trunk of letters owned by two former Dutch postmasters from the 1600s that helped advance our understanding of letter locking.
Back then, you had to pay to retrieve your letter from the post, so if you refused to pay or didn't come at all, the post office would keep your letter.
The trunk held 2,600 letters.
Nearly 600 of them had remained unopened since the 1600s.
These letters were such a rich source of not just everyday messages of people at the time, but also the ways in which letter locking was used by everyday people.
Scientists have now found a way that we can digitally unfold these letters so that we can read them without damaging the letter lock.
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