The clown’s bible

A man who would collect rare books happened to be chatting with one of his close friends. The friend told that recently he had thrown out a Bible, that had been in the family for generations. Also he mentioned something like Guten… was printed on it.
Stuck with doubt the man gasped, “It was not Gutenberg..right?”
“Yes, that was the name printed on it!” the friend replied.
“You idiot, you’ve thrown away one of the first books ever printed. Such a copy was sold at auction for $400,000 recently.”
“But mine wouldn’t have gone for such a price…because some clown by name Martin Luther had scribbled all over it.”
“…..!?!” (he fainted).