Letter from the Renaissance era sealed for centuries just practically unwrapped and read for the first time

More than 600 years ago, someone folded, sealed and posted a letter that was never delivered. Now, scientists have digitally “unfolded” this letter and other similarly blocked letters found in a 17th-century trunk in The Hague using X-rays.

Centuries before the invention of sealed envelopes, sensitive correspondence was protected from prying eyes by complex folding techniques called letterlocking, which turned a letter into its own secure envelope.

However, the blocked letters that survive to this day are fragile and can only be physically opened by cutting them into pieces.

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