A common type of secondhand customer, of course, comes questing after something particular, and not even the most maliciously disarranged shelving system can present a daunting obstacle. Somewhere in his home, on a high shelf of his own, is an empty spot of distinct width and depth. Only one book will fit there, so whenever said customer finds himself in strange neighborhoods, he is inevitably drawn hunching into bookstores and curio shops in the hope of locating the damn thing. Perhaps something known in childhood or college but long since lost, victim of toxic neglect or casual misplacement or fatal dog-chewing. Perhaps to complete a gap (or two) in a series collection, an ongoing endeavor. Perhaps known by reputation only, a notorious rarity, a variant. A first edition, first state. Signed.
My usual offer of We Don't Have It, But I Bet My Internet Knows Where It Is would only be taken about half the time. The other half would counter with a dismissive wave; not so much No Thanks as Get Outta Here With That Crap. You want some common reading copy of an obscure favorite for a gift or for a whim, that's one thing. But when the search is half the pleasure? That vacant spot on the bookshelf back home isn't crying to be filled so much as it is a license to darken the doors of every shabby-looking bookmonger along the way, every antiques emporium that might have a shelf or two of vintage pulps teetering in the back, to sniff the shadows in every dust-gilded corner, glide fingers across embossed spines of cloth and leather until some design pattern, some title, some name rises up to the light in your eyes. There's warm grace in finding a book by just such serendipity, so that it feels less like merely finding a book, more a nudge from the Universe into a set of coordinates no search engine is equipped to find, steady as she goes -- and secure in the knowledge that even as one distinctly-sized bookshelf gap is filled, another will fall open ...
What an astonishing thing a book is. It's a flat object made from a tree with flexible parts on which are imprinted lots of funny dark squiggles. But one glance at it and you're inside the mind of another person, maybe somebody dead for thousands of years. Across the millennia, an author is speaking clearly and silently inside your head, directly to you. Writing is perhaps the greatest of human inventions, binding together people who never knew each other, citizens of distant epochs. Books break the shackles of time. A book is proof that humans are capable of working magic.
-- Carl Sagan