“Saving clippings this way turns each book into a time capsule. The next time I open one of these books, a paper treasure will fall out. A little surprise for my future self. (Or whoever else cracks it open.)”Austin Kleon, “How to turn your books into time capsules.” AustinKleon.com. January 29, 2020.
Strangely, this even works when the time capsules are part of the creative product. I remember enjoying Ship of Theseus, largely for the meta-story and ephemera in the margins and added to the book. And, it also works when reading my own marginalia, years later. Adding clippings seems like a natural extension to capture the cultural moment.