In journeys at sea that took place before radio or radar or satellites or sonar, these logs were an indispensable source for recording what actually happened. They helped navigators surmise where they were and how far they had traveled and how much longer they had to stay at sea. They provided accountability to a ship’s owners and traders. They were designed to be as immune to faking as possible. Away from land, there was usually no reliable corroboration of events apart from the crew’s own account in the middle of an expanse of blue and gray and green; and in long journeys, memories always blur and facts disperse. A log provided as accurate an account as could be gleaned in real time.

As you read a log, you have the curious sense of moving backward in time as you move forward in pages—the opposite of a book. As you piece together a narrative that was never intended as one, it seems—and is—more truthful. Logs, in this sense, were a form of human self-correction. They amended for hindsight, for the ways in which human beings order and tidy and construct the story of their lives as they look back on them. Logs require a letting-go of narrative because they do not allow for a knowledge of the ending. So they have plot as well as dramatic irony—the reader will know the ending before the writer did.

Anyone who has blogged his thoughts for an extended time will recognize this world. We bloggers have scant opportunity to collect our thoughts, to wait until events have settled and a clear pattern emerges. We blog now—as news reaches us, as facts emerge. This is partly true for all journalism, which is, as its etymology suggests, daily writing, always subject to subsequent revision. And a good columnist will adjust position and judgment and even political loyalty over time, depending on events. But a blog is not so much daily writing as hourly writing. And with that level of timeliness, the provisionality of every word is even more pressing—and the risk of error or the thrill of prescience that much greater.

No columnist or reporter or novelist will have his minute shifts or constant small contradictions exposed as mercilessly as a blogger’s are. A columnist can ignore or duck a subject less noticeably than a blogger committing thoughts to pixels several times a day. A reporter can wait—must wait—until every source has confirmed. A novelist can spend months or years before committing words to the world. For bloggers, the deadline is always now. Blogging is therefore to writing what extreme sports are to athletics: more free-form, more accident-prone, less formal, more alive. It is, in many ways, writing out loud.

You end up writing about yourself, since you are a relatively fixed point in this constant interaction with the ideas and facts of the exterior world. And in this sense, the historic form closest to blogs is the diary. But with this difference: a diary is almost always a private matter. Its raw honesty, its dedication to marking life as it happens and remembering life as it was, makes it a terrestrial log. A few diaries are meant to be read by others, of course, just as correspondence could be—but usually posthumously, or as a way to compile facts for a more considered autobiographical rendering. But a blog, unlike a diary, is instantly public. It transforms this most personal and retrospective of forms into a painfully public and immediate one. It combines the confessional genre with the log form and exposes the author in a manner no author has ever been exposed before.

I remember first grappling with what to put on my blog. It was the spring of 2000 and, like many a freelance writer at the time, I had some vague notion that I needed to have a presence “online.” I had no clear idea of what to do, but a friend who ran a Web-design company offered to create a site for me, and, since I was technologically clueless, he also agreed to post various essays and columns as I wrote them. Before too long, this became a chore for him, and he called me one day to say he’d found an online platform that was so simple I could henceforth post all my writing myself. The platform was called Blogger.