An enigmatic message, long left unsolved, could reveal new theories about Munch's masterpiece.
"Could only have been painted by a madman!" ('Could only have been painted by a madman') reads the barely legible writing on the work.
This sentence, which is not really new, has been debated for about a century. Precisely since it was first mentioned in connection with an exhibition held in Copenhagen in 1904, eleven years after the artist painted the first version of the Scream, in 1893.