Amongst the many reasons to prefer a book over a file on your e-reader: books have history. Sometimes, the history is obvious and evident. A book might have memories attached to it, or sentimental value. Sometimes, however, the history is weird, twisted, and hidden. There’s an air of mystery to certain books, a thrill of an enigma, a hint of something outside the realm of normality.

Here’s a list of such books, ones that have stumped scholars and titillated bibliophiles. And while there’s plenty to be excited about with ebooks, the mysterious origins of a book are never going to translate to the new format.