The book no one has been able to read

There is a book, roughly 600 years old, written in an alphabet no one has managed to decipher.

It is called the Voynich manuscript. It is full of drawings of plants that do not exist, star maps and bathing figures, and a flowing text that looks like a real language… that neither the world's best cryptographers nor artificial intelligence have managed to read.

Six centuries on, it still keeps its secret in a library at Yale.