It's never intentional. I mean, I don't go looking for them. They appear like arrowheads and dry bones, sifted from the shifting sands of pages. I keep most of them, but as an unofficial rule, never reuse them. They stay in the books where they were found.
This is part of the reason I still buy used books. Of course, used books are cheaper, yes, but there is also a human connection there. The unseen community of readers. I receive each used book I buy from someone else, who may have gotten it from a third, and so on. And each dog-ear, each soup stain and inksmudge, is evidence of that community. Books aren't supposed to stand on shelves, pristine and uncreased, like the porcelain figurines of mom's that you were never allowed to go near. Books are meant to be read, used, kindly abused. Worn out, a bit. It's what makes them more...human.
Every once in a while, I find leftovers. Halfway through one book I bought last year (I can't remember which), there was a ticket stub from the Cincinnati Museum of Natural Science. The faded date was August of 2001. I imagined the reader being halfway through the book when the towers fell. Perhaps after that terrible reality, finishing a novel seemed unimportant, profane in a way. But there the ticket stub stayed, holding place, waiting.
I began "The Crying of Lot 49" today. When I started reading, the book fell open to about page 40, revealing a receipt for its purchase. The last reader bought it from London Drugs in Calgary. January 10, 1996. They paid 6.42 with their credit card. The credit card number is right there, all sixteen digits in Roman squads. I wonder who bought it. Why it was apparently bought at a drug store. Was the reader getting medicine and decided to add a good read to the prescription? Perhaps they were buying a card for someone's birthday, and got the book for themselves. So many possibilities. I wonder how this book, bought so far away, ended up on a used bookstore shelf in Houston.
I've found several such pieces of lives, ticket stubs, grocery lists, pieces of paper. Fragments of other readers, scattered across my path. I try to keep them. I've kept most. I've made my own, using fragments of flyers and notecards to hold my pages. I don't know if I've left any for other people, but I think that's the idea. I doubt highly that my Canadian friend intended on leaving me his/her credit card number. I don't think my Ohioan neighbor realized I would see when (s)he visited the dinosaur bones.
The point is not to leave notes for others, with a wink. To do so would be to present what you wish the next reader to see; and that's not reality. The joy of finding old notes and ticket stubs is in catching past readers unawares, sneaking into their lives for a moment, and snatching some of their unimportant shreds. I'm sure I've surprised unknown readers myself, informing them of what movies I've seen, and what I needed at Walmart. And that makes me happy. The cycle goes on.
The one idea that's always fascinated me, my one conceptual obsession, is the vast interconnectedness of people. Six degrees of Kevin Bacon on a global scale. And one small way I think these connections are made is through bookmarks, stamps, shopping lists, and love letters, jammed in the pages of paperbacks.