Since I've now entered some 200 of my books into LibraryThing, I've been spending a lot of time looking at copyright pages. It's interesting how the effort to catalog books, or to provide concrete, categorized information about them, has evolved over time. From my recent wealth of experience, the ISBN was created to help solve this issue around 1965 (turns out it was 1966).
Since then, CIP (the Library of Congress's Cataloging-in-Publication program) data has been added as a way to quickly summarize a book's metadata. But Oxford University Press has apparently recently decided to stop providing CIP data on their copyright pages, and even fails to include the book's ISBN, leaving the cataloger hunting on the back cover, where more often than not there are a few layers of dirtily peeling university bookstore price tags which prove irkingly difficult to remove. Why has OUP stopped providing CIP data? Is it because it looks so unintelligibly commercial? It seems awfully unkind to their books' cataloguers, of whom, let's face it, there will be tons since most of their books will end up in libraries.
Then there's a book I have by Rudyard Kipling. It's old, but nowhere in the book does there appear a single date. The only information on the copyright page is "Printed in the United States of America." This publisher, presumably from about a century ago, apparently did not care about including publication information. But the impulse to include metadata on or near the title page wasn't anything new in the twentieth century; I'm thinking primarily of the lavish self-description of John Bunyan's publisher, Nathaniel Ponder, who took all pains to put dates and his address etc., etc. in the first editions of "Pilgrim's Progress." Why would Kipling's American publisher leave all the info out? Is it a pirated edition? Does that matter?
Back to ISBNs, I've also managed to memorize the ISBN prefixes for several major publishers. It's a neat trick. "Oh, you read 0-14-043916-1 today? How do you like Penguin's new style for their Classics series?" I'm definitely going to bust that shit out at holiday parties. Good times.