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I think that Herge was probably worried that other artists would try to butcher Tintin
Actually, no - as well as the possibility of worse albums, he was quite clear that there were probably other artists and writers who could produce better
Tintin books than he could.
However, he saw the Tintin books as fundamentally an expression of him, both the strengths and the weaknesses, and that was why he wanted them to end - Tintin was him, and he was Tintin, and without him in the equation, it just wouldn't amount to the same thing.
This is the reason that his widow won't go against his wishes.
It's not a case of being right or wrong, of whether his request was or was not a mistake, it's emotional, and empathetic.
She's acutely aware that this is disappointing to many, many people, and it would undoubtedly be an extremely lucrative option to allow new books (the print runs on the new Asterix
books have been phenomenal, for example).
However, to do so would take an unbearable degree of heart-ache on her part: if you feel disappointed that there are no new books, think how bad she'd feel if she felt that she'd betrayed Hergé?
So, again, I say that while I wish you every success, and there's nothing impossible
about petioning for new books and getting a positive result, that it is highly unlikely that the position will change in the curent circumstances.