By Sarah Manguso, from Ongoingness: The End of a Diary, out in March from Graywolf Press. Manguso is the author of several books, including The Guardians and The Two Kinds of Decay.

I started keeping a diary twenty-five years ago. It’s 800,000 words long.

I didn’t want to lose anything. That was my main problem. I couldn’t face the end of a day without a record of everything that had ever happened.

I wrote about myself so I wouldn’t become paralyzed by rumination — so I could stop thinking about what had happened and be done with it.

More than that,…