The Kindle is changing a lot more about reading habits than we realize, writes Steven Johnson in a brilliant piece in today's Wall Street Journal. It is doing for books what the Internet (and Google) have already done for newspapers by making books and their contents instantly available. But the changes it will bring to all forms of publishing are even more profound.There are some obvious changes to how we interact with books in the offing: the Kindle will lead to more impulse purchases, and when someone recommends a title at lunch, you can simply download it on the spot, rather than jotting it down on a napkin or hoping you remember when you get home.

The Kindle may also lead to some unexpected and potentially unwanted changes in reading habits. For instance, it could bring the serendipitous, link-driven experience of Web-reading to books, which at this point are still read the old-fasioned way (from beginning to end, in an uninterrupted thought-stream relationship between reader and author).

Because they have been largely walled off from the world of hypertext, print books have remained a kind of game preserve for the endangered species of linear, deep-focus reading. Online, you can click happily from blog post to email thread to online New Yorker article -- sampling, commenting and forwarding as you go. But when you sit down with an old-fashioned book in your hand, the medium works naturally against such distractions; it compels you to follow the thread, to stay engaged with a single narrative or argument.

Books aren't formatted for easy search and reference, and no standard exists for doing so -- yet. But Johnson says you can expect publishers and authors to quickly do what Web publishers have been doing now for years -- optimizing books for Google search -- in order to benefit from the serendipitous nature of the Web. But then, and here's the truly interesting turn of the screw, as people and books start interacting with each other on the Web, readers are going to increasingly start sampling books by buying small parts -- chapters or even smaller increments.

Johnson points out that there isn't a standard for identifying portions of books -- page numbers are obsolete in the digital world -- to which people can link. It's time for publishers to get busy creating and agreeing to a standard so that it can become ubiquitous. Why?

The Kindle lets you pay small amounts of money for some things that are currently free on the Web -- like blog posts. I've already written about why I think Amazon's approach is a swindle, but Johnson makes the point that the Kindle's pricing strategy will change how people perceive paying for written content, and that the mechanism will suddenly exist for other types of publishers -- like newspapers - to monetize their content in tiny increments.

Breaking the book into detachable parts may sell more books, but there are certain kinds of experiences and arguments that can only be conveyed by the steady, directed immersion that a 400-page book gives you. A playlist of the best chapters from "Middlemarch," "Gravity's Rainbow" and "Beloved" will never work the way a playlist of songs culled from different albums does today... Yet that modular pricing system will have one interesting, and laudable, side effect: The online marketplace will have established an easy, one-click mechanism for purchasing small quantities of text.

The parallel of the Kindle and the Gilette razor is obvious: the Kindle is the razor and the content is the blades that Amazon wants to sell you. You could argue that the same is true with the iPod and iTunes. Amazon has already signaled how little the sale of Kindles actually matters in the long run by offering the Kindle iPhone app free of charge.

The most profound change, and perhaps the saddest, is that the Kindle will ultimately teach us that books, like razors, are disposable. It will become harder to hold readers' attention, and it will become more important than ever for authors to differentiate themselves and for newspapers to differentiate distinctions themselves. But the change is coming, and the faster authors and publishers embrace it, the sooner they'll be able to partake of the mass audience waiting to discover them online.