“We realized there was a whole hidden collection within the collection,” says Kristin Jensen, the manager of a project that archives the marginalia and materials found in circulating library collections around the world, in “Secrets Hidden in the Stacks” in the July/August issue of Poets & Writers Magazine. “Readers from the nineteenth century and early twentieth century, it turned out, used books as souvenirs, journals, greeting cards, funeral programs, and invitations, among myriad other purposes.” Write a short story in which a character uses the blank pages or margins of a book to write a diary entry or letter, or to press flowers. What’s the significance of the particular book chosen? Is there someone on the receiving end, or are the traces discovered years later by accident?