If you are going to collect books as physical objects, rather than their much more convenient digital versions, then it strikes me you should actually find the signs of previous interactions with that object (library stamps, marks from other readers etc) make them more interesting than pristine copies that no one has read.

I opened a bookshop after a long run in tech to try to slow down, and one of the pleasant surprises was the joy in accepting used book donations. I re-donate most of them, but have found some wonderful bookmarks and inscriptions in many. The words matter most, of course, but the tangible evidence of people decades or centuries ago is something that speaks to me profoundly. One inscription in a tiny book of prayers mentioned a friend passing it on after it had been placed under her deceased infant sister's chin, which was both morbid and moving. Autographs of spooks like J. Edgar Hoover conjure up other feelings. One other comment: the very old books will probably be around for a few centuries more after the newer ones have turned to dust.

I used to hang out at used bookstores regularly. Mostly to find cheap but good quality books for my kids when they were younger. I once managed to get a used copy of Paul Graham's On Lisp which was discarded from the technical library of a company somewhere.

The main point of interest is that physical items age and retain artifacts of their lives. I found a childrens book that was discarded from an American library where a girl had scrawled in pencil that she was proud that she finished it. I've seen one which was awarded to a man for being top of his class in college in the early 1900s. The bookshop I used to visit once had a book sold to him which contained a letter from Rabindrnath Tagore in the original in between the leaves of the book.

It's a fascinating feeling and quite primal.

I primarily read theology, and lots of early-to-mid-20th century Anglican theology. So, many of the books I read are out of print—and thus only available used. I’ve found that reading in a niche area tends to put some interesting copies in my lap. I have quite a few copies around that previously belonged to “famous” (at least within my little world) theologians. Many of these other copies are often ex-library, often from seminary or monastic libraries. It’s always interesting to see what libraries are getting rid of and to think about the monks or nuns who sat around reading them. (Or not, as the case may be—they were withdrawn, after all.)

My favorite is a copy of Martin Thornton’s The Function of Theology, which had been deaccessioned from the library of the Seminary of the Southwest at some point. I happened to flip to the back to glance at the loan card. It had been borrowed precisely one time—October 23, 1987—but it had been borrowed that one time by a priest who became a friend of mine in 2021 during a course at a different institution. The small world of Anglican theology! I texted him a picture of the book, and he still remembered checking it out.

Favorite ex-library book: "The Unix Environment" by A. N. Walker. Ex library: AT&T Bell Laboratories, Murray Hill, NY. Cost from Alibris: $1.