Mark Oppenheimer uses the moment of Amazon reporting that e-books sales have surpassed hardcovers to muse on some things, once public, that our digital culture now hides about us:

Remember when you could tell a lot about a guy by what cassette tapes—Journey or the Smiths?—littered the floor of his used station wagon? No more, because now the music of our lives is stored on MP3 players and iPhones. Our important papers live on hard drives or in the computing cloud, and DVDs are becoming obsolete, as we stream movies on demand. One by one, the meaningful artifacts that we used to scatter about our apartments and cars, disclosing our habits to any visitor, are vanishing from sight.

Nowhere is this problem more apparent, and more serious, than in the imperilment of the Public Book—the book that people identify us by because they can glimpse it on our bookshelves, or on a coffee table, or in our hands. As the Kindle and Nook march on, people’s reading choices will increasingly be hidden from view. We’ll go into people’s houses or squeeze next to them on the subway, and we’ll no longer be able to know them, or judge them, or love them, or reject them, based on the books they carry.

FUN STUFF: Go ahead, try it, judge a book by its cover.