Jammy History on Instagram: "Let’s learn about letter locking. At its core, letter locking involves any method of folding up a letter to make it harder to access its contents. Some of these methods were quite complex, or require a special tool to create which is the case with the ‘spiral lock’ method. But others are quite easy to replicate, such as the ‘triangle fold’ method used by Francis Walsingham as the spymaster to Queen Elizabeth I. The purpose of this technique was to make it impossible

Cracking the Code of Letterlocking