THIS is ridiculous. Mind boggling. Nonsensical. That link has 40 fore-edge paintings. Which is a technique of painting on the edges of the pages of a book. The artwork can only be seen when the pages are fanned. When the book is closed, you don’t see the image because it is hidden by the gilding. Four of the 40 are located at the University of Iowa: Special Collections & Archive library. Yay Iowa. The other 35 (there’s one other from a random library) are from the Boston Public Library. Oh of course they are. Crazy Boston. I miss you.
Anyway, check them out!